Note: Descriptions are shown in the official language in which they were submitted.
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GAS COMPRESSOR
TECHNICAL FIELD
[0001] The present disclosure relates to gas compressors driven by a
driving fluid
such as a hydraulic fluid, including hydraulic gas compressors driven by
hydraulic
fluid that are used in oil and gas field applications.
BACKGROUND
[0002] Various different types of gas compressors to compress a wide
range of
gases are known. Hydraulic gas compressors in particular are used in a number
of
different applications. One such category of, and application for, a is a gas
compressor employed in connection with the operation of oil and gas producing
well
systems. When oil is extracted from a reservoir using a well and pumping
system, it
is common for natural gas, often in solution, to also be present within the
reservoir.
As oil flows out of the reservoir and into the well a wellhead gas may be
formed as it
travels into the well and may collect within the well and /or travel within
the casing of
the well. The wellhead gas may be primarily natural gas and also includes
impurities
such as water, hydrogen sulphide, crude oil, and natural gas liquids (often
referred
to as condensate).
[0003] The presence of natural gas within the well can have negative
impacts on
the functioning of an oil and gas producing well system. It can for example
create a
back pressure on the reservoir at the bottom of the well shaft that inhibits
or restricts
the flow of oil to the well pump from the reservoir. Accordingly, it is often
desirable
to remove the natural gas from the well shaft to reduce the pressure at the
bottom of
the well shaft particularly in the vicinity of the well pump. Natural gas that
migrates
into the casing of the well shaft may be drawn upwards - such as by venting to
atmosphere or connecting the casing annulus to a pipe that allows for gas to
flow out
of the casing annulus. To further improve the flow of gas out of the casing
annulus
and reduce the pressure of the gas at the bottom of the well shaft, the
natural gas
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flowing from the casing annulus may be compressed by a gas compressor and then
may be utilized at the site of the well and/or transported for use elsewhere.
The use
of a gas compressor will further tend to create a lower pressure at the top of
the well
shaft compared to the bottom of the well shaft, assisting in the flow of
natural gas
upwards within the well bore and casing.
[0004] There are concerns in using hydraulic gas compressors in oil and
gas field
environments, relating to the potential contamination of the hydraulic fluid
in the
hydraulic cylinder of a gas compressor from components of the natural gas that
is
being compressed.
[0005] Improved gas compressors are desirable, including gas compressors
employed in connection with oil and gas field operations including in
connection with
oil and gas producing wells.
SUMMARY
[0006] In one embodiment, the present disclosure relates to a gas
compressor
system that comprises a driving fluid cylinder having a driving fluid chamber
adapted
for containing a driving fluid therein, and a driving fluid piston movable
within the
driving fluid chamber. A gas compression cylinder having a gas compression
chamber adapted for holding a gas therein and a gas piston movable within the
gas
compression chamber. A buffer chamber located between the driving fluid
chamber
and the gas compression chamber, the buffer chamber adapted to inhibit
movement
of at least one non-driving fluid component, when gas is located within the
gas
compression chamber, from the gas compression chamber into the driving fluid
chamber.
[0007] In another embodiment, the present disclosure relates to a gas
compressor system that comprises a first driving fluid cylinder having a first
driving
fluid chamber adapted for containing a first driving fluid therein, and a
first driving
fluid piston movable within the first driving fluid chamber. A gas compression
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chamber adapted for holding a gas therein and a gas piston movable within the
gas
compression chamber. A first buffer chamber located between the first driving
fluid
chamber and a first section of the gas compression chamber. A second driving
fluid
cylinder having a second driving fluid chamber adapted for containing a second
driving fluid therein, and a second driving fluid piston movable within the
second
driving fluid chamber. A second buffer chamber located between the first
driving
fluid chamber and a second section of the gas compression chamber. The first
buffer chamber is adapted to inhibit movement of at least one non-driving
fluid
component, when gas is located within a first section of the gas compression
chamber, from the first section gas compression chamber section into the first
driving fluid chamber. The second buffer chamber is adapted to inhibit
movement of
at least one non-driving fluid component, when gas is located within a second
section of the gas compression chamber, from the second section of the gas
compression chamber into the second driving fluid chamber.
[0008] In another embodiment, the present disclosure relates to a gas
compressor that comprises a driving fluid cylinder having a driving fluid
chamber
operable for containing a driving fluid therein and a driving fluid piston
movable
within the driving fluid chamber. A gas compression cylinder having a gas
compression chamber operable for holding a gas therein and a gas piston
movable
within the gas compression chamber. A buffer chamber located between the
driving
fluid chamber and the gas compression chamber, the buffer chamber configured
and
operable to inhibit movement of at least one non-driving fluid component from
the
gas compression chamber to substantially avoid contamination of the driving
fluid,
when gas is located within the gas compression chamber.
[0009] In another embodiment, the present disclosure relates to a gas
compressor that comprises a driving fluid cylinder having a driving fluid
chamber
operable for containing a driving fluid therein and a driving fluid piston
movable
within the driving fluid chamber. A gas compression cylinder having a gas
compression chamber operable for holding natural gas therein and a gas piston
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movable within the gas compression chamber. A buffer chamber located between
the driving fluid chamber and the gas compression chamber, the buffer chamber
containing a non-natural gas component so as to substantially avoid
contamination
of the driving fluid in the driving fluid chamber, when gas is located within
the gas
compression chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the figures, which illustrate example embodiments:
[0011] FIG. 1. is a schematic view of an oil and gas producing well
system;
[0012] FIG. 1A. is an enlarged schematic view of a portion of the system of
FIG. 1;
[0013] FIG. 1B is an enlarged view of part of the system of FIG. 1;
[0014] FIG. 1C is an enlarged view of another part of the system of FIG.
1;
[0015] FIG. 1D is a schematic view of an oil and gas well producing
system like
the system of FIG. 1 but with an alternate lift system;
[0016] FIG. 2 is a side view of a gas compressor forming part of the
system of
FIG. 1;
[0017] FIG. 3 (i) to (iv) are side views of the gas compressor or FIG. 2
showing a
cycle of operation;
[0018] FIG. 4 is a schematic side view of the gas compressor of FIG. 2;
[0019] FIG. 5 is a perspective view a gas compressor system including
the gas
compressor of FIG. 2 forming part of an oil and gas producing well
systems of FIG. 1 or 1D;
[0020] FIG. 6 is a perspective view of a potion of the gas compressor
system of
FIG. 5 with some parts thereof exploded;
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[0021] FIG. 7 is a schematic diagram of the gas compressor system of FIG.
8;
[0022] FIG. 8 is a perspective exploded view of a gas compressor
substantially
like the gas compressor of FIG. 2;
[0023] FIG. 8A is enlarged view of the portion marked FIG. 8A in FIG. 8;
[0024] FIG. 8B is enlarged view of the portion marked FIG. 8B in FIG. 8;
[0025] FIG. 9A is a perspective view of the gas compressor of FIG. 2;
[0026] FIG. 9B is a top view of the gas compressor of FIG. 2;
[0027] FIG. 9C is a side view of the gas compressor of FIG. 2.
DETAILED DESCRIPTION
[0028] With reference to FIGS. 1, 1A, 1B and 1C, an example oil and gas
producing well system 100 is illustrated schematically that may be installed
at, and
in, a well shaft (also referred to as a well bore) 108 and may be used for
extracting
liquid and/or gases (e.g. oil and/or natural gas) from an oil and gas bearing
reservoir
104.
[0029] Extraction of liquids including oil as well as other liquids such
as water
from reservoir 104 may be achieved by operation of a down-well pump 106
positioned at the bottom of well shaft 108. For extracting oil from reservoir
104,
down-well pump 106 may be operated by the up-and-down reciprocating motion of
a
sucker rod 110 that extends through the well shaft 108 to and out of a well
head 102.
It should be noted that in some applications, well shaft 108 may not be
oriented
entirely vertically, but may have horizontal components and/or portions to its
path.
[0030] Well shaft 108 may have along its length, one or more generally
hollow
cylindrical tubular, concentrically positioned, well casings 120a, 120b, 120c,
including an inner-most production casing 120a that may extend for
substantially the
entire length of the well shaft 108. Intermediate casing 120b may extend
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concentrically outside of production casing 120a for a substantial length of
the well
shaft 108, but not to the same depth as production casing 120a. Surface casing
120c may extend concentrically around both production casing 120a and
intermediate casing 120b, but may only extend from proximate the surface of
the
ground level, down a relatively short distance of the well shaft 108. The
casings
120a, 120b, 120c may be made from one or more suitable materials such as for
example steel. Casings 120a, 120b, 120c may function to hold back the
surrounding earth / other material in the sub-surface to maintain a generally
cylindrical tubular channel through the sub-surface into the oil / natural gas
bearing
formation 104. Casings 120a, 120b, 120c may each be secured and sealed by a
respective outer cylindrical layer of material such as layers of cement 111a,
111b,
111c which may be formed to surround casings 120a-120c in concentric tubes
that
extend substantially along the length of the respective casing 120a-120c.
Production tubing 113 may be received inside production casing 120a and may be
generally of a constant diameter along its length and have an inner tubing
passageway / annulus to facilitate the communication of liquids (eg. oil) from
the
bottom region of well shaft 108 to the surface region. Casings 120a-120c
generally,
and casing 120a in particular, can protect production tubing 120 from
corrosion,
wear/damage from use. Along with other components that constitute a production
string, a continuous passageway (a tubing annulus) 107 from the region of pump
106 within the reservoir 104 to well head 102 is provided by production tubing
113.
Tubing annulus 107 provides a passageway for sucker rod 110 to extend and
within
which to move and provides a channel for the flow of liquid (oil) from the
bottom
region of the well shaft 108 to the region of the surface.
[0031] An annular casing passageway or gap 121 (referred to herein as a
casing
annulus) is typically provided between the inward facing generally cylindrical
surface
of the production casing 120a and the outward facing generally cylindrical
surface of
production tubing 113. Casing annulus 121 typically extends along the co-
extensive
length of inner casing 120a and production tubing 113 and thus provides a
passageway / channel that extends from the bottom region of well shaft 108
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proximate the oil! gas bearing formation 104 to the ground surface region
proximate
the top of the well shaft 108. Natural gas (that may be in liquid form in the
reservoir
104) may flow from reservoir 104 into the well shaft 108 and may be, or
transform
into, a gaseous state and then flow upwards through casing annulus 121 towards
well head 102. In some situations, such as with a newly formed well shaft 108,
the
level of the liquid (mainly oil and natural gas in solution) may actually
extend a
significant way from the bottom/end of the well shaft 108 to close to the
surface in
both the tubing annulus 107 and the casing annulus 121, due to relatively high
downhole pressures.
[0032] Down-well pump 106 may have a plunger 103 that is attached to the
bottom end region of sucker rod 110 and plunger 103 may be moved downwardly
and upwardly within a pump chamber by sucker rod 110. Down well pump 106 may
include a one way travelling valve 112 which is a mobile check valve which is
interconnected with plunger 103 and which moves in up and down reciprocating
motion with the movement of sucker rod 110. Down well pump 106 may also
include a one way standing intake valve 114 that is stationary and attached to
the
bottom of the barrel of pump 106/ production tubing 113. Travelling valve 112
keeps the liquid (oil) in the channel 107 of production tubing 113 during the
upstroke
of the sucker rod 110. Standing valve 114 keeps the fluid (oil) in the channel
107 of
the production tubing 113 during the downstroke of sucker rod 110. During a
downstroke of sucker rod 110 and plunger 103, travelling valve 112 opens,
admitting
liquid (oil) from reservoir 104 into the annulus of production tubing 113 of
down-well
pump 106. During this downstroke, one-way standing valve 114 at the bottom of
well shaft 108 is closed, preventing liquid (oil) from escaping.
[0033] During each upstroke of sucker rod 110, plunger 103 of down-well
pump
106 is drawn upwardly and travelling valve 112 is closed. Thus, liquid (oil)
drawn in
through one-way valve 112 during the prior downstroke can be raised. And as
standing valve 114 opens during the upstroke, liquid (oil) can enter
production tubing
113 below plunger 103 through perforations 116 in production casing 120a and
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cement layer illa, and past standing valve 114. Successive upstrokes of down-
well pump 106 form a column of liquid/oil in well shaft 108 above down-well
pump
106. Once this column of liquid/oil is formed, each upstroke pushes a volume
of oil
toward the surface and well head 102. The liquid/oil, eventually reaches a T-
junction device 140 which has connected thereto an oil flow line 133. Oil flow
line
133 may contain a valve device 138 that is configured to permit oil to flow
only
towards a T-junction interconnection 134 to be mixed with compressed natural
gas
from piping 130 that is delivered from a gas compressor system 126 and then
together both flow way in a main oil/gas output flow line 132.
[0034] Sucker rod 110 may be actuated by a suitable lift system 118 that
may for
example as illustrated schematically in FIG. 1, be a pump jack system 119 that
may
include a walking beam mechanism 117 driven by a pump jack drive mechanism
120 (often referred to as a prime mover). Prime mover 120 may include a motor
123 that is powered for example by electricity or a supply of natural gas,
such as for
example, natural gas produced by oil and gas producing well system 100. Prime
move 120 may be interconnected to and drive a rotating counter weigh device
122
that may cause the pivoting movement of the walking beam mechanism 120 that
causes the reciprocating upward and downward movement of sucker rod 110.
[0035] As shown in FIG. 1 D, lift mechanism 118 may in other embodiments
be a
hydraulic lift system 1119 that includes a hydraulic fluid based power unit
1120 that
supplies hydraulic fluid through a fluid supply circuit to a master cylinder
apparatus
1117 to controllably raise and lower the sucker rod 110. The power unit 1120
may
include a suitable controller to control the operation of the hydraulic lift
system 1119.
[0036] With reference to FIGS. 1 to 1C, natural gas exiting from annulus
121 of
casing 120 may be fed by suitable piping 124 through valve device 128 to inter-
connected gas compressor system 126. Piping 124 may be made of any suitable
material(s) such as steel pipe or flexible hose such as Aeroquip FC 300 AOP
elastomer tubing made by Eaton Aeroquip LLC. In normal operation of system
100,
the flow of natural gas communicated through piping 124 to gas compressor
system
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126 is not restricted by valve device 128 and the natural gas will flow there
through.
Valve 128 may be closed (eg. manually) if for some reason it is desired to
shut off
the flow of natural gas from annulus 121.
[0037] Compressed natural gas that has been compressed by gas compressor
system 126 may be communicated via piping 130 through a one way check valve
device 131 to interconnect with oil flow line 133 to form a combined oil and
gas flow
line 132 which can deliver the oil and gas therein to a destination for
processing
and/or use. Piping 130 may be made of any suitable material(s) such as steel
pipe
or flexible hose such as Aeroquip FC 300 AOP elastomer tubing made by Eaton
Aeroquip LLC.
[0038] Gas compressor system 126 may include a gas compressor 150 that
is
driven by a driving fluid. As indicated above, natural gas from casing annulus
121
of well shaft 108 may be supplied by piping 124 to gas compressor system 126.
Natural gas may be compressed by gas compressor 150 and then communicated
via piping 130 through a one way check valve device 131 to interconnect with
oil
flow line 133 to form combined oil and gas flow line 132.
[0039] The driving fluid for driving gas compressor 150 may be any
suitable fluid
such as a fluid that is substantially incompressible, and may contain anti-
wear
additives or constituents. The driving fluid may, for example, be a suitable
hydraulic
fluid. For example, the hydraulic fluid may be SKYDROL TM aviation fluid
manufactured by Solutia Inc. The hydraulic fluid may for example be a fluid
suitable
as an automatic transmission fluid, a mineral oil, a bio-degradable hydraulic
oil, or
other suitable synthetic or semi-synthetic hydraulic fluid.
[0040] Hydraulic gas compressor 150 may be in hydraulic fluid
communication
with a hydraulic fluid supply system which may provide an open loop or closed
loop
hydraulic fluid supply circuit. For example gas compressor 150 may in
hydraulic
fluid communication with a hydraulic fluid supply system 1160 as depicted in
FIG.
10.
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[0041] Turning now to FIGS. 2 and 7, hydraulic gas compressor 150 may
have
first and second, one-way acting, hydraulic cylinders 152a, 152b positioned at
opposite ends of hydraulic gas compressor 150. Cylinders 152a, 152b are each
configured to provide a driving force that acts in an opposite direction to
each other,
both acting inwardly towards each other and towards a gas compression cylinder
180. Thus, positioned generally inwardly between hydraulic cylinders 152a,
152b is
gas compression cylinder 180. Gas compression cylinder 180 may be divided into
two gas compression chamber sections 181a, 181b by a gas piston 182. In this
way, gas such as natural gas in each of the gas chamber sections 181a, 181b,
may
be alternately compressed by alternating, inwardly directed driving forces of
the
hydraulic cylinders 152a, 152b driving the reciprocal movement of gas piston
182
and piston rod 194
[0042] Gas compression cylinder 180 and hydraulic cylinders 152a, 152b
may
have generally circular cross-sections although alternately shaped cross
sections
are possible in some embodiments.
[0043] Hydraulic cylinder 152a may have a hydraulic cylinder base 183a at
an
outer end thereof. A first hydraulic fluid chamber 186a may thus be formed
between
a cylinder barrel / tubular wall 187a, hydraulic cylinder base 183a and
hydraulic
piston 154a. Hydraulic cylinder base 183a may have a hydraulic input/output
fluid
connector 1184a that is adapted for connection to hydraulic fluid
communication line
1166a. Thus hydraulic fluid can be communicated into and out of first
hydraulic fluid
chamber 186a.
[0044] At the opposite end of gas compressor 150, is a similar
arrangement.
Hydraulic cylinder 152b has a hydraulic cylinder base 183b at an outer end
thereof.
A second hydraulic fluid chamber 186b may thus be formed between a cylinder
barrel / tubular wall 187b, hydraulic cylinder base 183b and hydraulic piston
154b.
Hydraulic cylinder base 183b may have an input /output fluid connector 1184b
that
is adapted for connection to a hydraulic fluid communication line 1166b. Thus
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hydraulic fluid can be communicated into and out of second hydraulic fluid
chamber
186b.
[0045] In embodiments such as is illustrated in FIG. 7, the driving
fluid connectors
1184a, 1184b may each connect to a single hydraulic line 1166a, 1166b that
may,
depending upon the operational configuration of the system, either be
communicating hydraulic fluid to, or communicating hydraulic fluid away from,
each
of hydraulic fluid chamber 186a and hydraulic fluid chamber 186b,
respectively.
However, other configurations for communicating hydraulic fluid to and from
hydraulic fluid chambers 186a, 186b are possible.
[0046] As indicated above, gas compression cylinder 180 is located
generally
between the two hydraulic cylinders 152a, 152b. Gas compression cylinder 180
may
be divided into the two adjacent gas chamber sections 181a, 181b by gas piston
182. First gas chamber section 181a may thus be defined by the cylinder barrel
/
tubular wall 190, gas piston 182 and first gas cylinder head 192a. The second
gas
chamber section 181b may thus be defined by the cylinder barrel/tubular wall
190,
gas piston 182 and second gas cylinder head 192b and formed on the opposite
side
of gas piston 182 to first gas chamber section 181a.
[0047] The components forming hydraulic cylinders 154a, 154b and gas
compression cylinder 180 may be made from any one or more suitable materials.
By
way of example, barrel 190 of gas compression cylinder 180 may be formed from
chrome plated steel; the barrel of hydraulic cylinders 152a, 152b, may be made
from
a suitable steel; gas piston 182 may be made from T6061aluminum; the hydraulic
pistons 154a, 154b may be made generally from ductile iron; and piston rod 194
may be made from induction hardened chrome plated steel.
[0048] The diameter of hydraulic pistons 154a, 154b may be selected
dependent
upon the required output gas pressure to be produced by gas compressor 150 and
a
diameter (for example about 3 inches) that is suitable to maintain a desired
pressure
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of hydraulic fluid in the hydraulic fluid chambers 186a, 186b (for example ¨ a
maximum pressure of about 2800 psi).
[0049] Hydraulic pistons 154a, 154b may also include seal devices 196a,
196b
respectively at their outer circumferential surface areas to provide fluid /
gas seals
with the inner wall surfaces of respective hydraulic cylinder barrels 187a,
187b
respectively. Seal devices 196a, 196b, may substantially prevent or inhibit
movement of hydraulic fluid out of hydraulic fluid chambers 186a, 186b during
operation of hydraulic gas compressor 150 and may prevent or at least inhibit
the
migration of any gas/liquid that may be in respective adjacent buffer chambers
195a,
195b (as described further hereafter) into hydraulic fluid chambers 186a,
186b.
[0050] Also with reference now to FIGS. 8, 8A and 8B, hydraulic piston
seal
devices 196a, 196b may include a plurality of olytetrafluoroethylene (PTFE)
(eg.Tef Ion (TM) seal rings and may also include Hydrogenated nitrile
butadiene
rubber (HNBR) energizers / energizing rings for the seal rings. A mounting nut
188a
188b may be threadably secured to the opposite ends of piston rod 194 and may
function to secure the respective hydraulic pistons 154a, 154b onto the end of
piston
rod 194.
[0051] The diameter of the gas piston 182 and corresponding inner
surface of
gas cylinder barrel 190 will vary depending upon the required volume of gas
and
may vary widely (eg. from about 6 inches to 12 inches or more). In one example
embodiment, hydraulic pistons 154a, 154b have a diameter of 3 inches; piston
rod
194 has a diameter or 2.5 inches and gas piston 182 has a diameter of 8
inches.
[0052] Gas piston 182 may also include a conventional gas compression
piston
seal device at its outer circumferential surfaces to provide a seal with the
inner wall
surface of gas cylinder barrel 190 to substantially prevent or inhibit
movement of
natural gas and any additional components associated with the natural gas,
between
gas compression cylinder sections 181a, 181b. Gas piston seal device may also
assist in maintaining the gas pressure differences between the adjacent gas
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compression cylinder sections 181a, 181b, during operation of hydraulic gas
compressor 150.
[0053] As noted above, hydraulic pistons 154a, 154b may be formed at
opposite
ends of a piston rod 194. Piston rod 194 may pass through gas compression
cylinder sections 181a, 181b and pass through a sealed (eg. by welding)
central
axial opening 191 through gas piston 182 and be configured and adapted so that
gas piston 182 is fixedly and sealably mounted to piston rod 194.
[0054] Piston rod 194 may also pass through axially oriented openings in
head
assemblies 200a, 200b that may be located at opposite ends of gas cylinder
barrel
190. Thus, reciprocating axial / longitudinal movement of piston rod 194 will
result in
reciprocating synchronous axial / longitudinal movement of each of hydraulic
pistons
154a, 154b in respective hydraulic fluid chambers 186a, 186b, and of gas
piston 182
within gas compression chamber sections 181a, 181b of gas compression cylinder
180.
[0055] Located on the inward side of hydraulic piston 154a, within
hydraulic
cylinder 154a, between hydraulic fluid chamber 186a and gas compression
cylinder
section 181a, may be located first buffer chamber 195a. Buffer chamber 195a
may
be defined by an inner surface of hydraulic piston 154a, the cylindrical inner
wall
surface of hydraulic cylinder barrel 187a, and hydraulic cylinder head 189a.
[0056] Similarly, located on the inward side of hydraulic piston 154b ,
within
hydraulic cylinder 154b, between hydraulic fluid chamber 186b and gas
compression cylinder section 181b, may be located second buffer chamber 195b.
Buffer chamber 195b may be defined by an inner surface of hydraulic piston
154b,
the cylindrical inner wall surface of cylinder barrel 187b, and hydraulic
cylinder head
189b.
[0057] As hydraulic pistons 154a, 154b are mounted at opposite ends of
piston
rod 194, piston rod 194 also passes through buffer chambers 195a, 195b.
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[0058] With particular reference now to FIGS. 2, 6, 8, 8A-C, and 9A-C and
13A-
C, head assembly 200a may include hydraulic cylinder head 189a and gas
cylinder
head 192a and a hollow tubular casing 201a. Hydraulic cylinder head 189a may
have a generally circular hydraulic cylinder head plate 206a formed or mounted
within casing 201a (FIG. 8B).
[0059] A barrel flange plate 290a (FIG. 9A), hydraulic cylinder head
plate 206a
(FIG. 8B) and a gas cylinder head plate 212a may have casing 201a disposed
there
between. Gas cylinder head plate 212a may be interconnected to an inward end
of
hollow tubular casing 201a for example by welds or the two parts may be
integrally
to formed together. In other embodiments, hollow tubular casing 201a may be
integrally formed with both hydraulic cylinder head plate 206a and gas
cylinder head
plate 212a.
[0060] Hydraulic cylinder barrel 187a may have an inward end 179a,
interconnected such as by welding to the outward facing edge surface of a
barrel
flange plate 290a. Barrel flange plate 290a may be configured as shown in
FIGS. 2,
8,8A-C, and 9A-C.
[0061] Barrel flange plate 290a may be connected to the hydraulic
cylinder head
plate 206a by bolts 217 (FIG. 8) received in threaded openings 218 of outward
facing surface 213a of hydraulic head plate 206a (FIGS. 8 and 8B). A gas and
liquid seal may be created between the mating surfaces of hydraulic head plate
206a and barrel flange plate 290a. A sealing device may be provided between
these plate surfaces such as TEFLON hydraulic seals and buffers.
[0062] Gas cylinder barrel 190 may have an end 155a (FIG. 8B)
interconnected
to the inward facing surface of gas cylinder head plate 212a such as by
passing first
threaded ends of each of the plurality of tie rods 193 through openings in
head plate
212a and securing them with nuts 168.
[0063] Piston rod 194 may have a portion that moves longitudinally within
the
inner cavity formed through openings within barrel flange plate 290a,
hydraulic
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cylinder head plate 206a and gas cylinder head plate 212a and within tubular
casing
210a.
[0064] A structure and functionality corresponding to the structure and
functionality just described in relation to hydraulic cylinder 152a, buffer
chamber
__ 195a, and gas compression cylinder section 181a, may be provided on the
opposite
side of hydraulic gas compression cylinder 150 in relation to hydraulic
cylinder 152b,
buffer chamber 195b, and gas compression cylinder section 181b.
[0065] Thus with particular reference to FIGS. 8, 8A and 8B, head
assembly
200b may include hydraulic cylinder head 189b, gas cylinder head 192b and a
__ hollow tubular casing 201b. Hydraulic cylinder head 189b may have a
hydraulic
cylinder head plate 206b formed or mounted within casing 201b (FIG. 8A)
[0066] A barrel flange plate 290b /hydraulic cylinder head plate 206b and
a gas
cylinder head plate 212b (FIGS. 8 and 8A) may have casing 201b generally
disposed there between. Gas cylinder head plate 212b may be interconnected to
__ hollow tubular casing 201b for example by welds or the two parts may be
integrally
formed together. In other embodiments, hollow tubular casing 201b may be
integrally formed with hydraulic cylinder head plate 206b and gas cylinder
head plate
212b.
[0067] Hydraulic cylinder barrel 187b (FIG. 9A) may have an inward end
179b,
__ interconnected such as by welding to the outward facing edge surface of a
barrel
flange plate 290b. Barrel flange plate 290b may also be configured as shown in
FIGS. 2, 8, 8A-C, and FIGS. 9A-C.
[0068] Barrel flange plate 290b may be connected to the hydraulic
cylinder head
plate 206b by bolts 217 received in threaded openings 218b of outward facing
__ surface 213b of hydraulic head plate 206b (FIG. 9B). A gas and liquid seal
may be
created between the mating surfaces of hydraulic head plate 206b and barrel
flange
plate 290b. A sealing device may be provided between these plate surfaces such
as
TEFLON hydraulic seals and buffers.
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[0069] Gas cylinder barrel 190 may have an end 155b (FIG. 9A)
interconnected
to the inward facing surface of gas cylinder head plate 212b such as by
passing first
threaded ends of each of the plurality of tie rods 193 through openings in
head plate
212b and securing them with nuts 168.
[0070] Piston rod 194 may have a portion that moves longitudinally within
the
inner cavity formed through openings within hydraulic cylinder head plate 206b
and
gas cylinder head plate 212b and within tubular casing 210b.
[0071] With particular reference now to FIGS. 8, 8A and 8B, two head
sealing 0-
rings 308a, 308b may be provided and which may be made from highly saturated
nitrile-butadiene rubber (HNBR). One 0-ring 308a may be located between a
first
circular edge groove 216a at end 155a of gas cylinder barrel 190 and the
inward
facing surface of gas cylinder head plate 212a. 0-ring 308a may be retained in
a
groove in the inward facing surface of gas cylinder head plate 212a. 0-ring
308b
may be located between a second opposite circular edge groove 216b of at the
opposite end of gas cylinder barrel 190 and the inward facing surface of gas
cylinder
head plate 212b. 0-ring 308b may be retained in a groove in the inward facing
surface of gas cylinder head plate 212b. In this way gas seals are provided
between
gas compression chamber sections181a, 181b and their respective gas cylinder
head plates 212a, 212b.
[0072] By securing threaded both opposite ends of each of the plurality of
tie rods
193 through openings in gas cylinder head plates 212a, 212b and securing them
with nuts 168, tie rods 193 will function to tie together the head plates 212a
and
212b with gas cylinder barrel 190 and 0-rings 308a, 308b securely held there
between and providing a sealed connection between cylinder barrel 190 and head
plates 212a, 212b.
[0073] Seal / wear devices 198a, 198b may be provided within casing 201a
to
provide a seal around piston rod 194 and with an inner surface of casing 201a
to
prevent or limit the movement of natural gas out of gas compression cylinder
section
16
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181a, into buffer chamber 195a. Corresponding seal / wear devices may be
provided within casing 201b to provide a seal around piston rod 194 and with
an
inner surface of casing 201b to prevent or limit the movement of natural gas
out of
gas compression cylinder section 181b, into buffer chamber 195b. These seal
devices198a, 198b may also prevent or at least limit/inhibit the movement of
other
components (such as contaminants) that have been transported with the natural
gas
from well shaft 108 into gas compression cylinder sections 181a, 181b, from
migrating into respective buffer chambers 195a, 195b.
[0074] While in some embodiments, the gas pressure in gas compression
chamber sections 181a, 181b will remain generally, if not always, above the
pressure in the adjacent respective buffer chambers 195a, 195b, the seal /
wear
devices 198a, 198b may in some situations prevent migration of gas and/or
liquid
that may be in buffer chambers 195a, 195b from migrating into respective gas
compression chamber sections 181a 181b. The seal / wear devices 198a, 198b
may also assist to guide piston rod 194 and keep piston rod 194 centred in the
casings 201a, 201b and absorb transverse forces exerted upon piston rod 194.
[0075] Also, with particular reference to FIGS. 8, 8A and 8B, each seal
device
198a, 198b may be mounted in a respective casing 201a, 201b. Associated with
each head assembly 200a, 200b may also be a rod seal retaining nut 151 which
may be made from any suitable material, such as for example aluminium bronze.
A
rod seal retaining nut 151 may be axially mounted around piston rod 194. Rod
seal
retaining nut 151 may be provided with inwardly directed threads 156. The
threads
156 of rod sealing nut 151 may engage with internal mating threads in opening
153
of the respective casing 201a, 201b. By tightening rod sealing nut 151,
components
of sealing devices 198a, 198b may be axially compressed within casing 201a,
201b.
The compression causes components of the sealing devices 198a, 1987b to be
pushed radially outwards to engage an inner cylindrical surface of the
respective
casings 201a, 201b and radially inwards to engage the piston rod 194. Thus
seal
17
CA 2961634 2017-03-20
devices 198a, 198b are provided to function as described above in providing a
sealing mechanism.
[0076] As each rod seal retaining nut 151 can be relatively easily
unthreaded
from engagement with its respective casing 201a, 201b, maintenance and/or
replacement of one or more components of seal devices 198a, 198b is made
easier.
Additionally, by turning a rod seal retaining nut 151 may be engaged to thread
the
rod seal retaining nut further into opening 153 of the casing, adjustments can
be
made to increase the compressive load on the components of the sealing devices
198a, 198b to cause them to be being pushed radially further outwards into
further
and stronger engagement with an inner cylindrical surface of the respective
casings
201a, 201b and further inwards to engage with the piston rod 194. Thus the
level of
sealing action /force provided by each seal device 198a, 198b may be adjusted.
[0077] However, even with an effective seal provided by the sealing
devices
198a, 198b, it is possible that small amounts of natural gas, and/or other
components such as hydrogen sulphide, water, oil may still at least in some
circumstances be able to travel past the sealing devices 198a, 198b into
respective
buffer chambers 195a, 195b For example, oil may be adhered to the surface of
piston rod 194 and during reciprocating movement of piston rod 194, it may
carry
such other components from the gas compression cylinder section 181a, 181b
past
sealing devices 198a, 198b, into an area of respective cylinder barrels 187a,
187b
that provide respective buffer chambers 195a, 195b. High temperatures that
typically occur within gas compression chamber sections 181a, 181b may
increase
the risk of contaminants being able to pass seal devices 198a, 198b. However
buffer chambers 195a, 195b each provide an area that may tend to hold any
contaminants that move from respective gas compression chamber sections 181a,
181b and restrict the movement of such contaminants into the areas of cylinder
barrels that provide hydraulic cylinder fluid chambers 186a, 186b.
[0078] Mounted on and extending within cylinder barrel 187a close to
hydraulic
cylinder head 189a, is a proximity sensor 157a. Proximity sensor 157a is
operable
18
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such that during operation of gas compressor 150, as piston 154a is moving
from left
to right, just before piston 154a reaches the position shown in FIG. 3(i),
proximity
sensor 157a will detect the presence of hydraulic piston 154a within hydraulic
cylinder 152a at a longitudinal position that is shortly before the end of the
stroke.
Sensor 157a will then send a signal to controller 200, in response to which
controller
200 can take steps to change the operational mode of hydraulic fluid supply
system
1160 (FIG. 7).
[0079] Similarly, mounted on and extending within cylinder barrel 187b
close to
hydraulic cylinder head 189b, is another proximity sensor 157b. Proximity
sensor
157b is operable such that during operation of gas compressor 150, as piston
154b
is moving from right to left, just before piston 154b reaches the position
shown in
FIG. 5(iii), proximity sensor 157b will detect the presence of hydraulic
piston 154b
within hydraulic cylinder 152b at a longitudinal position that is shortly
before the end
of the stroke. Proximity sensor 157b will then send a signal to controller
200, in
response to which controller 200 can take steps to change the operational mode
of
hydraulic fluid supply system 1160.
[0080] Proximity sensors 157a, 157b may be in communication with
controller
200. In some embodiments, proximity sensors 157a, 157b may be implemented
using inductive proximity sensors, such as model BI 2--M12-Y1X-H1141 sensors
manufactured by Turck, Inc. These inductive sensors are operable to generate
proximity signals responsive to the proximity of a metal portion of piston rod
194
proximate to each of hydraulic piston 154a, 154b. For example sensor rings may
be
attached around piston rod 194 at suitable positions towards, but spaced from,
hydraulic pistons 154a, 154b respectively such as annular collar 199b in
relation to
hydraulic piston 154b - FIGS. 6 and 8. Proximity sensors 157a, 157b may detect
when collars 199a, 199b on piston rod 194 pass by. Steel annular collars 199a,
199b may be mounted to piston rod 194 and may be held on piston rod 194 with
set
screws and a LOCTITE TM adhesive made by Henkel Corporation.
19
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[0081] It is possible for controller 200 (FIG. 7) to be programmed in
such manner
to control the hydraulic fluid supply system 1160 in such a manner as to
provide for
a relatively smooth slowing down, a stop, reversal in direction and speeding
up of
piston rod 194 along with the hydraulic pistons 154a, 154b and gas piston 182
as
the piston rod 194, hydraulic pistons 154a, 154b and gas piston 182 transition
between a drive stroke providing movement to the right to a drive stroke
providing
the stroke to the left and back to a stroke providing movement to the right.
[0082] An example hydraulic fluid supply system 1160 for driving
hydraulic
pistons 154a, 154b of hydraulic cylinders 152a, 152b of hydraulic gas
compressor
150 in reciprocating movement is illustrated in FIG. 7. Hydraulic fluid supply
subsystem 1160 may be a closed loop system and may include a pump unit 1174,
hydraulic fluid communication lines 1163a, 1163b, 1166a, 1166b, and a hot oil
shuttle valve device 1168. Shuttle valve device 1168 may be for example a hot
oil
shuttle valve device made by Sun Hydraulics Corporation under model XRDCLNN-
AL.
[0083] Fluid communication line 1163a fluidly connects a port S of pump
unit
1174 to a port 0 of shuttle valve 1168. Fluid communication line 1163b fluidly
connects a port P of pump 1174 to a port R of shuttle valve 1168. Fluid
communication line 1166a fluidly connects a port V of shuttle valve 1168 to a
port
1184a of hydraulic cylinder 152a. Fluid communication line 1166b fluidly
connects a
port W of shuttle valve 1168 to a port 1184b of hydraulic cylinder 152b.
[0084] An output port M of shuttle valve 1168 may be connected to an
upstream
end of a bypass fluid communication line 1169 having a first portion 1169a, a
second
portion 1169b and a third portion 1169c that are arranged in series A filter
1171
may be interposed in bypass line 1169 between portions 1169a and 1169b. Filter
1171 may be operable to remove contaminants from hydraulic fluid flowing from
shuttle valve device 1168 before it is returned to reservoir 1172. Filter 1171
may for
example include a type HMK05/25 5 micro-m filter device made by Donaldson
Company, Inc. The downstream end of line portion 1169b joins with the upstream
CA 2961634 2017-03-20
end of line portion 1169c at a T-junction where a downstream end of a pump
case
drain line 1161 is also fluidly connected. Case drain line 1161 may drain
hydraulic
fluid leaking within pump unit 1174. Fluid communication line portion 1169c is
connected at an opposite end to an input port of a thermal valve device 1142.
Depending upon the temperature of the hydraulic fluid flowing into thermal
valve
device 1142 from communication line portion 1169c of bypass line 1169, thermal
valve device 1142 directs the hydraulic fluid to either fluid communication
line 1141a
or 1141b. If the temperature of the hydraulic fluid flowing into thermal valve
device
1142 is greater than a set threshold level, valve device 1142 will direct the
hydraulic
fluid through fluid communication line 1141a to a cooling device 1143 where
hydraulic fluid can be cooled before being passed through fluid communication
line
1141c to reservoir 1172. If the hydraulic fluid entering fluid valve device
1142 does
not require cooling, then thermal valve 1142 will direct the hydraulic fluid
received
therein from communication line portion 1169c to communication line 1141b
which
leads directly to reservoir 1172. An example of a suitable thermal valve
device 1142
is a model 67365-110F made by TTP (formerly Thermal Transfer Products). An
example of a suitable cooler 1143 is a a model BOL-16-216943 also made by TTP.
[0085] Drain line 1161 connects output case drain ports U and T of pump
unit
1174 to a T-connection in communication line 1169b at a location after filter
1171.
Thus any hydraulic fluid directed out of case drain ports U / T of pump unit
1174 can
pass through drain line 1161 to the T-connection of communication line
portions
1169b, 1169c, (without going through the filter device 1171) where it can mix
with
any hydraulic fluid flowing from filter 1171 and then flow to thermal valve
device
1142 where it can either be directed to cooler 1143 before flowing to
reservoir 1172
or be directed directly to reservoir 1172. By not passing hydraulic fluid from
case
drain 1161 through relatively fine filter 1171, the risk of filter 1171 being
clogged can
be reduced. It will be noted that filter 1182 provides a secondary filter for
fluid that
is re-charging pump unit 1174 from reservoir 1172.
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[0086] Hydraulic fluid supply system 1160 may include a reservoir 1172
may
utilize any suitable driving fluid, which may be any suitable hydraulic fluid
that is
suitable for driving the hydraulic cylinders 152a, 152b.
[0087] Cooler 1143 may be operable to maintain the hydraulic fluid
within a
desired temperature range, thus maintaining a desired viscosity. For example,
in
some embodiments, cooler 1143 may be operable to cool the hydraulic fluid when
the temperature goes above about 50 C and to stop cooling when the temperature
falls below about 45 C. In some applications such as where the ambient
temperature of the environment can become very cold, cooler 1143 may be a
combined heater and cooler and may further be operable to heat the hydraulic
fluid
when the temperature reduces below for example about -10 C. The hydraulic
fluid
may be selected to maintain a viscosity generally in hydraulic fluid supply
system
1160 of between about 20 and about 40 MM2S-1 over this temperature range.
[0088] Hydraulic pump unit 1174 is generally part of a closed loop
hydraulic fluid
supply system 1160. Pump unit 1174 includes outlet ports S and P for
selectively
and alternately delivering a pressurized flow of hydraulic fluid to fluid
communication
lines 1163a and 1163b respectively, and for allowing hydraulic fluid to be
returned to
pump unit 1174 at ports Sand P. Thus hydraulic fluid supply system 1160 may be
part of a closed loop hydraulic circuit, except to the extent described
hereinafter.
Pump unit 1174 may be implemented using a variable-displacement hydraulic pump
capable of producing a controlled flow hydraulic fluid alternately at the
outlets S and
P. In one embodiment, pump unit 1174 may be an axial piston pump having a
swashplate that is configurable at a varying angle a. For example pump unit
1174
may be a HPV-02 variable pump manufactured by Linde Hydraulics GmBH & Co.
KG of Germany, a model that is operable to deliver displacement of hydraulic
fluid of
up to about 55 cubic centimeters per revolution at pressures in the range of
58-145
psi. In other embodiments, the pump unit 1174 may be other suitable variable
displacement pump, such as a variable piston pump or a rotary vane pump, for
example. For the Linde HPV-02 variable pump, the angle a of the swashplate may
22
CA 2961634 2017-03-20
be adjusted from a maximum negative angle of about -21 , which may correspond
to
a maximum flow rate condition at the outlet S, to about 00, corresponding to a
substantially no flow condition from either port S or P, and a maximum
positive angle
of about +21 , which corresponds to a maximum flow rate condition at the
outlet P.
[0089] In this embodiment the pump unit 1174 may include an electrical
input for
receiving a displacement control signal from controller 200. The displacement
control signal at the input is operable to drive a coil of a solenoid (not
shown) for
controlling the displacement of the pump unit 1174 and thus a hydraulic fluid
flow
rate produced alternately at the outlets P and S. The electrical input is
connected to
a 24VDC coil within the hydraulic pump 1174, which is actuated in response to
a
controlled pulse width modulated (PWM) excitation current of between about 232
mA (ion) for a no flow condition and about 425 mA (iu) for a maximum flow
condition.
[0090] For the Linde HPV-02 variable pump unit 1174, the swashplate is
actuated
to move to an angle a either +21 or -21 , only when a signal is received from
controller 200. Controller 200 will provide such a signal to pump unit 1174
based on
the position of the hydraulic pistons 154a, 154b as detected by proximity
sensors
157a, 157b as described above, which provide a signal to the controller 200
when
the gas compressor 150 is approaching the end of a drive stroke in one
direction,
and commencement of a drive stroke in the opposite direction is required.
[0091] Pump unit 1174 may also have be part of a fluid charge system 1180.
Fluid charge system 1180 is operable to maintain sufficient hydraulic fluid
within
pump unit 1174 and may maintain/hold fluid pressure of for example at least
300 psi
at both ports S and P so as to be able to control and maintain the operation
of the
main pump so it can function to supply a flow of hydraulic fluid under
pressure
alternately at ports S and P.
[0092] Fluid charge system 1180 may include a charge pump that may be a
16cc
charge pump supplying for example 6-7 gpm and it may be incorporated as part
of
pump unit 1174. Charge system 1180 functions to supply hydraulic fluid as may
be
23
CA 2961634 2017-03-20
required by pump unit 1174, to replace any hydraulic fluid that may be
directed from
port M of shuttle valve device 1168 through a relief valve associated with
shuttle
valve device 1168 to reservoir 1172 and to address any internal hydraulic
fluid
leakage associated with pump unit 1174. The shuttle valve device 1168 may for
example redirect in the range of 3-4 gpm from the hydraulic fluid circuit. The
charge
pump will then replace the redirected hydraulic fluid 1:1 by maintain a low
side loop
pressure.
[0093] The relief valve associated with shuttle valve device 1168 will
typically
only divert to port M a very small proportion of the total amount of hydraulic
fluid
circulating in the fluid circuit and which passes through shuttle valve device
1168
into and out of hydraulic cylinders 152a, 152b. For example, the relief valve
associated with shuttle valve device may only divert approximately 3 to 4
gallons per
minute of hydraulic fluid at 200 psi, accounting for example only about 1% of
the
hydraulic fluid in the substantially closed loop the hydraulic fluid circuit.
This allows
at least a portion of the hydraulic fluid being circulated to gas compressor
150 on
each cycle to be cooled and filtered.
[0094] The charge pump may draw hydraulic fluid from reservoir 1172 on a
fluid
communication line 1185 that connects reservoir 1172 with an input port B of
pump
unit 1174. The charge pump of pump unit 1174 then directs and forces that
fluid to
port A where it is then communicated on fluid communication line 1181 to a
filter
device 1182 (which may for example be a 10 micro-m filter made by Linde.
[0095] Upon passing through filter device 1182 the hydraulic fluid may
then enter
port F of pump unit 1174 where it will be directed to the fluid circuit that
supplies
hydraulic fluid at ports S and P. In this way a minimum of 300 psi of pressure
of the
hydraulic fluid may be maintained during operation at ports S and P. The
charge
pressure gear pump may mounted on the rear of the main pump and driven through
a common internal shaft.
24
CA 2961634 2017-03-20
[0096] In a swashplate pump, rotation of the swashplate drives a set of
axially
oriented pistons (not shown) to generate fluid flow. In an embodiment of
Figure 10,
the swashplate of the pump unit 1174 is driven by a rotating shaft 1173 that
is
coupled to a prime mover 1175 for receiving a drive torque. In some
embodiments,
prime mover 1175 is an electric motor but in other embodiments, the prime
mover
may be implemented in other ways such as for example by using a diesel engine,
gasoline engine, or a gas driven turbine.
[0097] Prime mover 1175 is responsive to a control signal received from
controller 200 at a control input to deliver a controlled substantially
constant
1() rotational speed and torque at the shaft 1173. While there may be some
minor
variations in rotational speed, the shaft 1173 may be driven at a speed that
is
substantially constant and can for a period of time required, produce a
substantially
constant flow of fluid alternately at the outlet ports S and P. In one
embodiment the
prime mover 256 is selected and configured to deliver a rotational speed of
about
1750 rpm which is controlled to be substantially constant within about 1%.
[0098] To alternately drive the hydraulic cylinders 152a, 152b to
provide the
reciprocating axial motion of the hydraulic pistons 154a, 154b and thus
reciprocating
motion of gas piston 182, a displacement control signal is sent from
controller 200 to
pump unit 1174 and a signal is also provided by controller to prime mover
1175. In
response, prime mover 1175 drives rotating shaft 1173, to drive the swashplate
in
rotation. The displacement control signal at the input of pump unit 1174
drives a coil
of a solenoid (not shown) to cause the angle a of the swashplate to be
adjusted to
desired angle such as a maximum negative angle of about -21 , which may
correspond to a maximum flow rate condition at the outlet S and no flow at
outlet P.
The result is that pressurized hydraulic fluid is driven from port S of pump
unit 1174
along fluid communication line 1163a to input port Q of shuttle valve device
1168.
The shuttle valve device 1168 with the lower pressure hydraulic fluid at port
R will be
configured such that the pressurized hydraulic fluid flows into port Q will
flow out port
V of shuttle valve device 1168 and into and along fluid communication line
1166a
CA 2961634 2017-03-20
and then will enter hydraulic fluid chamber 186a of hydraulic cylinder 152a.
The flow
of hydraulic fluid into hydraulic fluid chamber 186a will cause hydraulic
piston 154a
to be driven axially in a manner which expands hydraulic fluid chamber 186a,
thus
resulting in movement in one direction of piston rod 194, hydraulic pistons
154a,
154b and gas piston 182.
[0099] During the expansion of hydraulic fluid chamber 186a as piston
154a
moves within cylinder barrel 187a, there will be a corresponding contraction
in size
of hydraulic fluid chamber 186b of hydraulic cylinder 152b within cylinder
barrel
187b. This results in hydraulic fluid being driven out of hydraulic fluid
chamber 186b
through port 1184b and into and along fluid communication line 1166b. The
configuration of shuttle valve device 1168 will be such that on this
relatively low
pressure side, hydraulic fluid can flow into port W and out of port R of
shuttle valve
device 1168, then along fluid communication line 1163b to port P of pump unit
1174.
However, the relief valve associated with shuttle valve device 1168 may in
this
operational configuration, direct a small portion of the hydraulic fluid
flowing along
line 1166b to port M for communication to reservoir 1172, as discussed above.
However, most (eg. about 99%) of the hydraulic fluid flowing in communication
line
1166b will be directed to communication line 1163b for return to pump unit
1174 and
enter at port P.
[00100] When the hydraulic piston 154a approaches the end of its drive
stroke,
a signal is sent by proximity sensor 157a to controller 200 which causes
controller
200 to send a displacement control signal to pump unit 1174. In response to
receiving the displacement control signal at the input of pump unit 1174, a
coil of the
solenoid (not shown) is driven to cause the angle a of the swashplate of pump
unit
1174 to be altered such as to be set at a maximum negative angle of about +210
,
which may correspond to a maximum flow rate condition at the outlet P and no
flow
at outlet S. The result is that pressurized hydraulic fluid is driven from
port P of
pump unit 1174 along fluid communication line 1163b to port R of shuttle valve
device 1168. The configuration of shuttle valve device 1168 will have been
adjusted
26
CA 2961634 2017-03-20
due lathe change in relative pressures of hydraulic fluid in lines 1163a and
1163b,
such that on this relatively high pressure side, hydraulic fluid can flow into
port R and
out of port W of shuttle valve device 1168, then along fluid communication
line
1166b to port 1184b. Pressurized hydraulic fluid will then enter hydraulic
fluid
chamber 186b of hydraulic cylinder 152b. This will cause hydraulic piston 154b
to be
driven in an opposite axial direction in a manner which expands hydraulic
fluid
chamber 186b, thus resulting in synchronized movement in an opposite direction
of
hydraulic cylinders 154a, 154b and gas piston 182.
[00101] During the expansion of hydraulic fluid chamber 186b, there
will be a
corresponding contraction of hydraulic fluid chamber 186a of hydraulic
cylinder
152a. This results in hydraulic fluid being driven out of hydraulic fluid
chamber 186a
through port 1184a and into and along fluid communication line 1166a. The
configuration of shuttle valve device 1168 will be such that on what is now
now a
relatively low pressure side, hydraulic fluid can now flow into port V and out
of port Q
of shuttle valve device 1168, then along fluid communication line 1163a to
port S of
pump unit 1174. However, the relief valve associated with shuttle valve device
1168 may in this operational configuration, direct as small portion of the
hydraulic
fluid flowing along line 1166a to port M for communication to reservoir 1172,
as
discussed above. Again most of the hydraulic fluid flowing in communication
line
1166a will be directed to communication line 1163a for return to pump unit
1174 at
port S but a small portion (eg. 1%) may be directed by shuttle valve device
1168 to
port M for communication to reservoir 1172, as discussed above. However, most
(eg. about 99%) of the hydraulic fluid flowing in communication line 1166a
will be
directed to communication line 1163a for return to pump unit 1174 and enter at
port S.
[00102] The foregoing describes one cycle which can be repeated
continuously
for multiple cycles, as may be required during operation of gas compressor
system
126. If a change in flow rate! fluid pressure is required in hydraulic fluid
supply
system 1160, to change the speed of movement and increase the frequency of the
27
CA 2961634 2017-03-20
cycles, controller 200 may send an appropriate signal to prime mover 1175 to
vary
the output to vary the rotational speed of shaft 1173. Alternately and/or
additionally,
controller 200 may send a displacement control signal to the input of pump
unit 1174
to drives the solenoid (not shown) to cause a different angle a of the
swashplate to
provide different flow rate conditions at the port P and no flow at outlet S
or to
provide different flow rate conditions at the port S and no flow at outlet P.
If zero
flow is required, the swash plate may be moved to an angle of zero degrees.
[00103] Controller 200 may also include an input for receiving a start
signal
operable to cause the controller 200 to start operation of gas compressor
system
lo 126 and outputs for producing a control signal for controlling operation
of the prime
mover 1175 and pump unit 1174. The start signal may be provided by a start
button
within an enclosure that is depressed by an operator on site to commence
operation.
Alternatively, the start signal may be received from a remotely located
controller,
which may be communication with the controller via a wireless or wired
connection.
The controller 200 may be implemented using a microcontroller circuit although
in
other embodiments, the controller may be implemented as an application
specific
integrated circuit (ASIC) or other integrated circuit, a digital signal
processor, an
analog controller, a hardwired electronic or logic circuit, or using a
programmable
logic device or gate array, for example.
[00104] With reference now to Figure 4, it may be appreciated that
hydraulic
cylinder barrel 187a may be divided into three zones: (i) a zone ZH dedicated
exclusively to holding hydraulic fluid; (ii) a zone ZB dedicated exclusively
for the
buffer area and (iii) a overlap zone that which, depending upon where the
hydraulic
piston 154a is in the stroke cycle, will vary between an area holding
hydraulic fluid
and an area providing part of the buffer chamber. Hydraulic cylinder barrel
187b
may be divided into a corresponding set of three zones in the same manner with
reference to the movement of hydraulic piston 154b.
[00105] If the length XBa (which is the length of the cylinder barrel
from gas
cylinder head 192a to the inward facing surface of hydraulic cylinder 154a at
its full
28
CA 2961634 2017-03-20
right position) is greater than the stroke length Xs, then any point 131a on
piston rod
194 on the piston rod 194 that is at least for part of the stroke within gas
compression chamber section 181a, will not move beyond the distance XBa when
the gas piston 182 and the hydraulic cylinder 154a move from the farthermost
right
positions of the stroke position (1) to the farthermost left positions of the
stroke
position (2). Thus, any materials/contaminants carried on piston rod 194
starting at
P1 a will not move beyond the area of the hydraulic cylinder barrel 187a that
is
dedicated to providing buffer chamber 195a. Thus, any such contaminants
travelling
on piston rod 194 will be prevented, or at least inhibited, from moving into
the zones
ZH and Zo of hydraulic cylinder barrel 187a that hold hydraulic fluid. Thus
any point
131 a on piston rod 194 that passes into the gas compression chamber will not
pass
into an area of the hydraulic cylinder barrel 187a that will encounter
hydraulic fluid
(ie. It will not pass into Zh or Zo). Thus, all portions of piston rod 194
that encounter
gas, will not be exposed to an area that is directly exposed to hydraulic
fluid. Thus
cross contamination of contaminants that may be present with the natural gas
in the
gas compression cylinder 180 may be prevented or inhibited from migrating into
the
hydraulic fluid that is in that areas of hydraulic cylinder barrel 187a
adapted for
holding hydraulic fluid. It may be appreciated, that since there is an overlap
zone,
the hydraulic pistons do move from a zone where there should be never anything
but
hydraulic fluid to a zone which transitions between hydraulic fluid and the
contents
(eg. air) of the buffer zone. Therefore, contaminants on the inner surface
wall of the
cylinder barrel 187a, 187b in the overlap zone could theoretically get
transferred to
the edge surface of the piston. However, the presence of buffer zone
significantly
reduces the level of risk of cross contamination of contaminants into the
hydraulic
fluid.
[00106] With reference continuing to Figure 4, it may be appreciated
that
hydraulic cylinder barrel 187b may also be divided into three zones - like
hydraulic
cylinder barrel 187a, namely: (i) a zone ZH dedicated exclusively to holding
hydraulic fluid; (ii) a zone ZB dedicated exclusively for the buffer area and
(iii) a
overlap zone that which, depending upon where the device is in the stroke
cycle, will
29
CA 2961634 2017-03-20
vary between an area holding hydraulic fluid and an area providing part of the
buffer
chamber.
[00107] If the length XBb (which is the length of the cylinder barrel
from gas
cylinder head 192b to the inward facing surface of hydraulic cylinder 152b at
its full
right position) is greater than the stroke length Xs, then any point P1b on
piston rod
194 will not move beyond the distance XBb when the gas piston 182 and the
hydraulic cylinder 154b move from the farthermost right positions of the
stroke (1) to
the farthermost left positions of the stroke (2). Thus any
materials/contaminants on
piston rod 194 starting at P1b will be prevented or at least inhibited from
moving
beyond the area of the hydraulic cylinder barrel 187b that provides buffer
chamber
195b. Thus, any such contaminants travelling on piston rod 194 will be
prevented,
or at least inhibited, from moving into the zones ZH and Zo of hydraulic
cylinder
barrel 187b that hold hydraulic fluid. Thus any point P2b on piston rod 194
that
passes into the gas compression chamber will not pass into an area of the
hydraulic
cylinder barrel 187b that will encounter hydraulic fluid (ie. It will not pass
into Zh or
Zo). Thus, all portions of piston rod 194 that encounter gas, will not be
exposed to
an area that is directly exposed to hydraulic fluid. Thus cross contamination
of
contaminants that may be present with the natural gas in the gas compression
cylinder 180 may be prevented or inhibited from migrating into the hydraulic
fluid that
is in that areas of hydraulic cylinder barrel 187b adapted for holding
hydraulic fluid.
Thus, any such contaminants travelling on piston rod 194 will be prevented or
a least
inhibited from moving into the area of hydraulic cylinder barrel 187b that in
operation, holds hydraulic fluid. Thus cross contamination of contaminants
that may
be present with the natural gas in the gas compression cylinder 180 may be
prevented or at least inhibited from migrating into the hydraulic fluid that
is in that
area of hydraulic cylinder barrel 187b that is used to hold hydraulic fluid.
[00108] In some embodiments, during operation of hydraulic gas
compressor
150, buffer chambers 195a, 195b may each be separately open to ambient air,
such
that air within buffer chamber may be exchanged with the external environment
(eg.
CA 2961634 2017-03-20
air at ambient pressure and temperature). However, it may not desirable for
the air
in buffer chambers 195a, 195b to be discharged into the environment and
possibly
other components to be discharged directly into the environment, due to the
potential for other components that are not environmentally friendly also
being
present with the air. Thus a closed system may be highly undesirable such that
for
example buffer chambers 195a, 195b may be in communication with each such that
a substantially constant amount of gas (eg. such as air) can be shuttled back
and
forth through communication lines ¨ such as communication lines 215a, 215b in
FIG. 7.
[00109] Buffer chambers 195a and/or 195b may in some embodiments be
adapted to function as a purge region. For example, buffer chambers 195a, 195b
may be fluidly interconnected to each other, and may also in some embodiments,
be
in fluid communication with a common pressurized gas regulator system 214
(Figure 7), through gas lines 215a, 215b respectively. Pressurized gas
regulator
system 214 may for example maintain a gas at a desired gas pressure within
buffer
chambers 195a, 195b that is always above the pressure of the compressed
natural
gas and/or other gases that are communicated into and compressed in gas
compression cylinder chamber sections 181a, 181b respectively. For example,
pressurized gas regulator system 214 may provide a buffer gas such as purified
natural gas, air, or purified nitrogen gas, or another inert gas, within
buffer chambers
195a, 195b. This may then prevent or substantially restrict natural gas and
any
contaminants contained in gas compression cylinder sections 181a, 181b
migrating
into buffer chambers 195a, 195b. The high pressure buffer gas in buffer
chambers
195a, 195b may prevent movement of natural gas and possibly contaminants into
the buffer chambers 195a, 195b. Furthermore if the buffer gas is inert, any
gas that
seeps into the gas compression cylinder chamber sections 181a, 181b will not
react
with the natural gas and/or contaminants. This can be particularly beneficial
if for
example the contaminants include hydrogen sulphide gas which may be present in
one or both of gas compression cylinder chamber sections 181a, 181b.
31
CA 2961634 2017-03-20
[00110] In some embodiments, gas lines 215a, 215b (FIG. 7) may not be
in
fluid communication with a pressurized gas regulator system 214 ¨ but instead
may
be interconnected directly with each other to provide a substantially
unobstructed
communication channel for whatever gas is in buffer chambers 195a, 195b. Thus
during operation of gas compressor 150, as hydraulic pistons 154a, 154b move
right
and then left (and/or upwards downwards) in unison, as one buffer chamber (eg.
buffer chamber 195a) increases in size, the other buffer chamber (eg. buffer
chamber 195b) will decrease in size. So instead of gas in in each buffer
chamber
195a, 195b being alternately compressed and then de-compressed, a fixed total
volume of gas at a substantially constant pressure may permit gas thereof to
shuttle
between the buffer chambers 195a, 195b in a buffer chamber circuit.
[00111] Also, instead of being directly connected with each other,
buffer
chambers 195a, 195b may be both in communication with a common holding tank
1214 (FIG. 7) that may provide a source of gas that may be communicated
between
buffer chambers 195a, 195b. The gas in the buffer chamber gas circuit may be
at
ambient pressure in some embodiments and pressurized in other embodiments.
The holding tank 1214 may in some embodiments also serve as a separation tank
whereby any liquids being transferred with the gas in the buffer chamber
system can
be drained off.
[00112] In the embodiment of FIGS. 2, and 9A-9C, a drainage port 207a for
buffer chamber 195a may be provided on an underside surface of hydraulic
cylinder
barrel 187a. A corresponding drainage port 207b may be provided for buffer
chamber 195b. Drainage ports 207a, 207b may allow drainage of any liquids that
may have accumulated in each of buffer chambers 195a, 195b respectively.
Alternately or additionally such liquids may be able to be drained from an
outlet in a
holding tank 1214.
[00113] As illustrated in FIGS. 5 and 6, gas compressor system 126 may
include a cabinet enclosure 1290 for holding components of hydraulic fluid
supply
system 1160 including pump unit 1174, prime mover 1175, reservoir 1172,
shuttle
32
CA 2961634 2017-03-20
device 1168, filters 1182 and 1171, thermal valve device 1142 and cooler 1143.
Controller 200 may also be held in cabinet enclosure 1290. One or more
electrical
cables 1291 may be provided to provide power and communication pathways with
the components of gas compressor system 126 that are mounted on a support
frame 1292. Additionally, piping 124 (FIG. 1) carrying natural gas to
compressor
150 may be connected to connector 250 when gas compressor 150 is mounted on
support frame 1292 to provide a supply of natural gas to gas compressor 150.
[00114] Gas compressor system 126 may thus also include a support
frame
1292. Support frame 1292 may be generally configured to support gas compressor
150 in a generally horizontal orientation. Support frame 1292 may include a
longitudinally extending hollow tubular beam member 1295 which may be made
from any suitable material such as steel or aluminium. Beam member 1295 may be
supported proximate each longitudinal end by pairs of support legs 1293a,
1293b
which may be attached to beam member 1295 such as by welding. Pairs of support
legs 1293a, 1293b may be transversely braced by transversely braced support
members 1294a, 1294b respectively that are attached thereto such as by
welding.
Support legs 1293a, 1293b and brace members 1294a, 1294b may be made also
be made from any suitable material such as steel or aluminium.
[00115] Mounted to an upper surface of beam member 1295 may be L-
shaped,
transversely oriented support brackets 1298a, 1298b that may be appropriately
longitudinally spaced from each other (see also FIGS. 8 to 9C). Support
brackets
1298a, 1298b may be secured to beam member 1295 by U-members 1299a, 1299b
respectively that are secured around the outer surface of beam member 1295 and
then secured to support brackets 1298a, 1298b by passing threaded ends through
openings 1300a, 1300b and securing the ends with pairs of nuts 1303a, 1303b
(FIG.
6). Support bracket 1298a may be secured to gas cylinder head plate 212a by
bolts
1302 received through aligned openings in support bracket 1298a and gas
cylinder
head plate 212a, secured by nuts 1301. Similarly, support bracket 1298b may be
secured to gas cylinder head plate 212b by bolts 1302 received through aligned
33
CA 2961634 2017-03-20
openings in support bracket 1298b and gas cylinder head plate 212, secured by
nuts
1301. In this way, gas compressor 150 may be securely mounted to and supported
by support frame 1292.
[00116] Hydraulic fluid communication lines 1166a, 1166b extend from
ports
184a, 184b respectively to opposite ends of support frame 1294 and may extend
under a lower surface of beam member 1295 to a common central location where
they may then extend together to enclosure cabinet 1290 housing shuttle valve
device 1168.
[00117] Tubular beam member 1295 maybe hollow and may be configured to
act as, or to hold a separate tank such as, holding tank 1214. Thus beam
member
1285 may serve to act as a gas / liquid separation and holding tank and may
serve
to provide a gas reservoir for gas for buffer chamber system of buffer
chambers
195a, 195b. Lines 215a, 215b may lead from ports of buffer chambers 195a, 195b
into ports 1305a, 1305b into holding tank 1214 within tubular member 1295.
[00118] Holding tank 1214 within beam member 1295 may also have an
externally accessible tank vent 1296 that allow for gas in holding tank 1214
to be
vented out. Also, holding tank 1214 may have a manual drain device 1297 that
is
also externally accessible and may be manually operable by an operator to
permit
liquids that may accumulate in holding tank 1214 to be removed.
[00119] In operation of gas compressor system 126 including hydraulic gas
compressor 150, the reciprocal movement of the hydraulic pistons 152a, 152b,
can
be driven by a hydraulic fluid supply system such as for example hydraulic
fluid
supply system 1160 as described above. The reciprocal movement of hydraulic
pistons 154a, 154b will cause the size of the buffer chambers 195a, 195b to
grow
smaller and larger, with the change in size of the two buffer chambers 195a,
195b
being for example 180 degrees out of phase with each other. Thus, as hydraulic
piston 154b moves from position 1 to position 2 in FIG. 6 driven by hydraulic
fluid
forced into hydraulic fluid chamber 186b, some of the gas (eg. air) in buffer
chamber
34
CA 2961634 2017-03-20
195b will be forced into gas line(s) 215a, 215b (FIG. 7) that interconnect
chambers
195a, 195b, and flow through holding tank 1214 towards and into buffer chamber
195a. In the reverse direction, as hydraulic piston 154a moves from position 2
to
position 1 in FIG. 4 driven by hydraulic fluid forced into hydraulic fluid
chamber 186a,
some of the gas (eg air) in buffer chamber 195a will be forced into gas lines
215a,
215b and flow through holding tank 1214 towards and into buffer chamber 195b.
In
this way, the gas in the system of buffer chambers 195a, 195b can be part of a
closed loop system, and gas may simply shuttle between the two buffer chambers
195a, 195b, (and optionally through holding tank 1214) thus preventing
1() contaminants that may move into buffer chambers 195a, 195b from gas
cylinder
sections 181a, 181b respectively, from contaminating the outside environment.
Additionally, such a closed loop system can prevent any contaminants in the
outside
environment from entering the buffer chambers 195a, 195b and thus potentially
migrating into the hydraulic fluid chambers 186a, 186b respectively.
[00120] Gas compressor system 126 may also include a natural gas
communication system to allow natural gas to be delivered from piping 124
(FIG. 1)
to the two gas compression chamber sections 181a, 181b of gas compression
cylinder 180 of gas compressor 150, and then communicate the compressed
natural
gas from the sections 181a, 181b to piping 130 for delivery to oil and gas
flow line
133.
[00121] With reference to FIG. 2 in particular, the natural gas
communication
system may include a first input valve and connector device 250, a second
input
valve and connector device 260, a first output valve and connector device 261
and a
second output valve and connector device 251. A gas input suction distribution
line
204 fluidly interconnects input valve and connector device 250 with input
valve and
connector device 260. A gas output pressure distribution line 209 fluidly
interconnects output valve and connector device 261with valve and connector
device 251.
CA 2961634 2017-03-20
[00122] With reference also to FIGS. 8, 8A and 8B, input valve and
connector
device 250 may include a gas compression chamber section valve and connector,
a
gas pipe input connector, and a gas suction distribution line connector. In an
embodiment as shown in FIGS. 2 and 3(i) to (iv) an excess pressure valve and
bypass connector is also provided. In an alternate embodiment as shown in
FIGS. 8
to 9C, there is no bypass connector. However, in this latter embodiment there
is a
lubrication connector 1255 to which is attached in series to an input port of
a
lubrication device 1256 comprising suitable fittings and valves. Lubrication
device
1256 allows a lubricant such as a lubricating oil (like WD-40 oil) to be
injected into
the passageway where the natural gas passes though connector device 250. The
WD40 can be used to dissolve hydrocarbon sludges and soots to keep seals
functional.
[00123] An electronic gas pressure sensing / transducer device 1257
may also
be provided which may for example be a model AST46HAP00300PGT1L000 made
by American Sensor technologies. This sensor reads the casing gas pressure.
[00124] Gas pressure sensing device! transducer 1257 may be in
electronic
communication with controller 200 and may provide signals to controller 200
indicative of the pressure of the gas in the casing / gas distribution line
204. In
response to such signal, controller 200 may modify the operation of system 100
and
in particular the operation of hydraulic fluid supply system 1160. For
example, if the
pressure in gas suction distribution line 204 descends to a first threshold
level (eg. 8
psi), controller 200 can control the operation of hydraulic fluid supply
system 170 to
slow down the reciprocating motion of gas compressor 150, which should allow
the
pressure of the gas that is being fed to connector device 250 and gas suction
distribution line 204 to increase. If the pressure measured by sensing device
1257
reaches a second lower threshold ¨ such that it may be getting close to zero
or
negative pressure (eg. 3 psi) controller 200 may cause hydraulic fluid supply
system
1160 to cease the operation of gas compressor 150.
36
CA 2961634 2017-03-20
[00125] Hydraulic fluid supply system 1160 may then be re-started by
controller
200, if and when the pressure measured by gas pressure sensing device /
transducer 1257 again rises to an acceptable threshold level as detected by a
signal
received by controller 200.
[00126] The output port of gas pressure sensing device 1257 may be
connected to an input connector of gas suction distribution line 204.
[00127] With reference to FIGS. 8A and 8B, output valve and connector
device
251 may include a gas compression chamber section valve, gas pipe output
connector 205 and a gas pressure distribution line connector 263. In an
embodiment as shown in FIG. 2, an excess pressure valve and bypass connector
is
also provided. In an alternate embodiment as shown in FIGS. 8 to 9C, there is
no
bypass connector.
[00128] With reference to the embodiment of FIGS. 2 and 3(i) to 3(iv),
a
pressure relief valve 265 is provided limit the gas discharge pressure. In
some
embodiments, relief valve 265 may discharge pressurized gas to the
environment.
However, in this illustrated embodiment, the relieved gas can be sent back
through a
bypass hose 266 to the suction side of the gas compressor 150 to limit
environmental discharge. One end of a bypass hose 266 may be connected for
communication of natural gas from a port of an excess gas pressure bypass
valve
265 (FIG. 2). The opposite end of bypass port may be connected to an input
port of
connector 250. The output port from bypass valve 265 may provide one way fluid
communication through bypass hose 266 of excessively pressured gas in for
example gas output distribution line 209, to connector 250 and back to the gas
input
side of gas compressor 150. Thus, once the pressure is reduced the pressure to
a
level that is suitable for transmission in piping 120 (FIG. 2A) gas pressure
relief
valve will close.
[00129] With reference to FIGS. 8 and 8B, installed within connector
250 is a
one way check valve device 1250. When connector 250 is received in an opening
37
CA 2961634 2017-03-20
1270 on the inward seal side of casing 201a, gas may flow through connector
250
and its check valve device 1250, through casing 201a into gas compression
chamber section 181a. Similarly within connector 251 is a one way check valve
device 1251. When connector 262 is received in an opening 1271 on the inward
seal side of casing 201b, gas may flow out of gas compression chamber section
181a through casing 201a, and then through one-way valve device 1251 of
connector 251 where gas can then flow through output connector 205 (FIG. 2)
into
piping 130 (FIG. 1).
[00130] The check valve device 1250 associated with connector 250 is
operable to allow gas to flow into casing 201a and gas compression chamber
section 181a, if the gas pressure at connector 250 is higher than the gas
pressure
on the inward side of the check valve device 1250. This will occur for example
when
gas compression chamber section 181a is undergoing expansion in size as gas
piston 182 moves away from head assembly 200a resulting in a drop in pressure
within compression chamber section 181a. Check valve device 1251 is operable
to
allow gas to flow out of casing 201a and gas compression chamber section 181a,
if
the gas pressure in gas compression chamber section 181a and casing 201a is
higher than the gas pressure on the outward side of check valve device 1251 of
connector 251, and when the gas pressure reaches a certain minimum threshold
pressure that allows it to open. The check valve device 1251 may be operable
to be
adjusted to set the threshold opening pressure difference that causes/allows
the one
way valve to open. The increase in pressure gas compression chamber section
181a and casing 201a will occur for example when gas compression chamber
section 181a is undergoing reduction in size as gas piston 182 moves towards
from
head assembly 200a resulting in an increase in pressure within compression
chamber section 181a.
[00131] With reference to FIG. 8, at the opposite end of gas suction
distribution
line 204 to the end connected to gas pressure sensing device 1257, is a second
input connector 260. Installed within connector 260 is a one way check valve
device
38
CA 2961634 2017-03-20
1260. When connector 260 is received in an opening on the inward seal side of
casing 201b, gas may flow from gas distribution line 204 through connector 260
and
valve device 1260, through casing 201b into gas compression chamber section
181b.
[00132] Similarly at the opposite end of gas pressure distribution line 209
to the
end connected to connector 210, is an output connector 261. Installed within
connector 261 is a one way check valve device 1261. When connector 261 is
received in an opening on the inward seal side of casing 201 b, gas may flow
out of
gas compression chamber section 181b through casing 201b and then through
valve device 1261 and connector 261 where pressurized gas can then flow
through
gas pressure distribution line 209 to output connector 205 and into piping 130
(FIG.
1).
[00133] One way check valve device 1260 is operable to allow gas to
flow into
casing 201b and gas compression chamber section 181b, if the gas pressure at
connector 260 is higher than the gas pressure on the inward side of check
valve
device 1260. This will occur for example when gas compression chamber section
181b is undergoing expansion in size as gas piston 182 moves away from head
assembly 200b resulting in a drop in pressure within compression chamber
section
181 b. One way check valve device 1261 is operable to allow gas to flow out of
casing 201b and gas compression chamber section 181b, if the gas pressure in
gas
compression chamber section 181b and casing 201b is higher than the gas
pressure on the outward side of check valve device 1261 of connector 261, and
when the gas pressure reaches a certain minimum threshold pressure that allows
it
to open. The check valve device 1261 may be operable to be adjusted to set the
threshold opening pressure difference that causes/allows the one way valve to
open.
The increase in pressure gas compression chamber section 181b and casing 201b
will occur for example when gas compression chamber section 181b is undergoing
reduction in size as gas piston 182 moves towards from head assembly 200b
resulting in an increase in pressure within compression chamber section 181b.
39
CA 2961634 2017-03-20
[00134] With particular reference to FIG. 8B, interposed between an
output end
of gas pressure distribution line 209 and valve and connector 251 may be a
bypass
valve 1265. If the gas pressure in gas pressure distribution line 209 and/or
in
connector 250, reaches or exceeds a pre-determined upper pressure threshold
level, excess pressure valve 1265 will open to relieve the pressure and reduce
the
pressure to a level that is suitable for transmission into piping 130 (FIG.
1).
[00135] In operation of gas compressor 150, hydraulic pistons 154a,
154b may
be driven in reciprocating longitudinal movement for example by hydraulic
fluid
supply system 1160 as described above, thus driving gas piston 182 as well.
The
following describes the operation of the gas flow and gas compression in gas
compressor system 126.
[00136] With hydraulic pistons 154a, 154b and gas piston 182 in the
positions
shown in FIG. 3(i) natural gas will be already located in gas cylinder
compression
section 181a, having been previously drawn into gas cylinder compression
section
181a during the previous stroke due to pressure the differential that develops
between the outer side of one way valve device 1250 and the inner side of
valve
device 1250 as piston 182 moved from left to right. During that previous
stroke,
natural gas will have been drawn from pipe 124 through connector 202 and
connector device 250 and its check valve device 1250 into gas compression
chamber section 181a, with check valve 1251 of connector device 251 being
closed
due to the pressure differential between the inner side of check valve device
1251
and the outer side of check valve device 1251 thus allowing gas compression
cylinder section 181a to be filled with natural gas at a lower pressure than
the gas on
the outside of connector device 251.
[00137] Thus, with the pistons in the positions shown in FIG. 3(i),
hydraulic
cylinder chamber 186b is supplied with pressurized hydraulic fluid in a manner
such
as is described above, thus driving hydraulic piston 154b, along with piston
rod 194,
gas piston 182 and hydraulic piston 154a attached to piston rod 194, from the
position shown in FIG. 3(i) to the position shown in FIG. 3(ii). As this is
occurring,
CA 2961634 2017-03-20
hydraulic fluid in hydraulic cylinder chamber 186a will be forced out of
chamber
186a, and flow as described above.
[00138] As hydraulic piston 154b, along with piston rod 194, gas
piston 182
and hydraulic piston 154a attached to piston rod 194, move from the position
shown
in FIG. 3(i) to the position shown in FIG. 3(11), natural gas will be drawn
from supply
line 124, through connector device 250 into gas suction distribution line 204,
and
then pass through input valve connector 260 and one way valve device 1260 and
into gas compression section 181b. Natural gas will flow in such a manner
because
as gas piston 182 moves to the left as shown in FIGS. 3(i) to (ii), the
pressure in gas
compression chamber 181b will drop, which will create a suction that will
cause the
natural gas in pipe 124 to flow.
[00139] Simultaneously, the movement of gas piston 182 to the left,
will
compress the natural gas that is already present in gas compression chamber
section 181a. As the pressure rises in gas chamber section 181a, gas flowing
into
connector 250 from pipe 124 will not enter chamber section 181a. Additionally,
gas
being compressed in gas compression chamber section 181a will stay in gas
compression chamber section 181a until the pressure therein reaches the
threshold
level of gas pressure that is provided by one way check valve device 1251. Gas
being compressed in chamber section 181a can't flow out of chamber section
181a
into connector 250 because of the orientation of check valve device 1250.
[00140] The foregoing movement and compression of natural gas and
movement of hydraulic fluid will continue as the pistons continue to move from
the
positions shown in FIG. 3(11) to the position shown in FIG. 3(111). During
that time,
dependent upon the pressure in gas compression chamber section 181a, gas will
be
allowed to pass out of gas compression chamber section 181a through connector
251 and will pass into piping 130 once the pressure is high enough to activate
one
way valve device 1251.
41
CA 2961634 2017-03-20
[00141] Just before hydraulic piston 154b reaches the position shown
in FIG.
3(iii), proximity sensor 157b will detect the presence of hydraulic piston
154b within
hydraulic cylinder 152b at a longitudinal position that is a short distance
before the
end of the stroke within hydraulic cylinder 152b. Proximity sensor 157b will
then
send a signal to controller 200, in response to which controller 200 will
change the
operational configuration of hydraulic fluid supply system 1160, as described
above.
This will result in hydraulic piston 154b not being driven any further to the
left in
hydraulic cylinder 152b than the position shown in FIG. 3(iii).
[00142] Once hydraulic piston 154b, along with piston rod 194, gas
piston 182
and hydraulic piston 154a attached to piston rod 194, are in the position
shown in
FIG. 3(iii), natural gas will have been drawn through connector 260 and one
way
valve device 1260 again due to the pressure differential that is developed
between
gas compression chamber section 181b and gas suction distribution pipe 204, so
that gas compression chamber section 181b is filled with natural gas. Much of
the
gas in gas compression chamber 181a that has been compressed by the movement
of gas piston 182 from the position shown in FIG. 3(i) to the position shown
in FIG.
3(iii), will, once compressed sufficiently to exceed the threshold level of
valve device
1251, have exited gas compression chamber 181a and pass from gas pipeline
output connector 205 into piping 130 (FIG. 1) for delivery to oil and gas
pipeline 133.
If the gas pressure is too high to be received in piping 130, excess valve and
bypass
connector 265/1265 will be opened to allow excess gas to exit to reduce the
pressure.
[00143] Next, gas compressor system 126, including hydraulic fluid
supply
system 1160 is reconfigured for the return drive stroke. As natural gas has
been
drawn into gas compression cylinder section 181b it is ready to be compressed
by
gas piston 182. With hydraulic pistons 154a, 154b and gas piston 182 in the
positions shown in FIG. 3(iii), hydraulic cylinder chamber 186a is supplied
with
pressurized hydraulic fluid by hydraulic fluid supply system 1160 for example
as
described above. This movement drives hydraulic piston 154a, along with piston
rod
42
CA 2961634 2017-03-20
194, gas piston 182 and hydraulic piston 154a attached to piston rod 194, from
the
position shown in FIG. 3(iii) to the position shown in FIG. 3(iv). As this is
occurring,
hydraulic fluid in hydraulic cylinder chamber 186b will be forced out of the
hydraulic
fluid chamber 186a and may be handled by hydraulic fluid supply system 1160 as
described above.
[00144] As hydraulic piston 154a, along with piston rod 194, gas
piston 182
and hydraulic piston 154b attached to piston rod 194, move from the position
shown
in FIG. 5(iii) to the position shown in FIG. 3(iv), natural gas will be drawn
from
supply line 124, through connector 253 of valve and connector device 250 into
gas
compression section 181a due the drop in pressure of gas in gas compression
section 181a, relative to the gas pressure in supply line 124 and the outside
of
connector 250. Simultaneously, the movement of gas piston 182 will compress
the
natural gas that is already present in gas compression section 181b. As the
gas in
gas compression chamber 181b is being compressed by the movement of gas
piston 182, once the gas pressure reaches the threshold level of valve device
1261
to be activated, gas will be able to exit gas compression chamber 181b and
pass
through connector 261, into gas pressure distribution line 209 and then pass
through
output connector 205 into piping 130 (FIG. 3) for delivery to oil and gas
pipeline 133.
Again, if the gas pressure is too high to be received in piping 130, excess
valve and
bypass connector 265/1265 will be opened to allow excess gas to exit to reduce
the
gas pressure in gas pressure distribution line 209 and piping 130.
[00145] The foregoing movement and compression of natural gas and
hydraulic fluid will continue as the pistons continue to move from the
positions
shown in FIG. 3(iv) to return to the position shown in FIG. 3(i). Just before
piston
154a reaches the position shown in FIG. 3(i), proximity sensor 157a will
detect the
presence of hydraulic piston 154a within hydraulic cylinder 152a at a
longitudinal
position that is shortly before the end of the stroke within hydraulic
cylinder 152a.
Proximity sensor 157a will then send a signal to controller 200, in response
to which
controller 200 will reconfigure the operational mode of hydraulic fluid supply
system
43
CA 2961634 2017-03-20
1160 as described above. This will result in hydraulic piston 154a not be
driven any
further to the right than the position shown in FIG. 3(i).
[00146] Once hydraulic piston 154a, along with piston rod 194, gas
piston 182
and hydraulic piston 154b attached to piston rod 194, are in the position
shown in
FIG. 3(i), natural gas will have been drawn through valve and connector 253 so
that
gas compression chamber section 181a is once again filled and controller 200
will
send a signal to the hydraulic fluid supply system 1160 so that gas compressor
system 126 is ready to commence another cycle of operation.
[00147] During the operation of the gas compressor 150 as described
above,
any contaminants that may be carried with the natural gas from supply pipe 124
will
enter into gas compression chamber sections 181a, 181b. However, the
components of seal devices 198a, 198b associated with casings 201a, 201b, as
described above, will provide a barrier preventing, or at least significantly
limiting,
the migration of any contaminants out of gas compression chamber sections
181a,
181b. However, any contaminants that do pass seal devices 198a, 198b are
likely
to be held in respective buffer chambers 195a, 195b and in combination with
seal
devices 196a, 196b of hydraulic pistons 154a, 154b respectively, may prevent
contaminants from entering into the respective hydraulic cylinder chambers
186a,
186b Particularly if buffer chambers 195a, 195b are pressurized, such as with
pressurized air or a pressurized inert gas, then this should greatly restrict
or inhibit
the movement of contaminants in the natural gas in gas compression chamber
sections 181a, 181b from migrating into buffer chambers 195a, 195b, thus
further
protecting the hydraulic fluid in hydraulic cylinder chambers 186a, 186b.
[00148] It should be noted that in use, hydraulic gas compressor 150
may be
oriented generally horizontally, generally vertically, or at an angle to both
vertical and
horizontal directions.
[00149] While the gas compressor system 126 that is illustrated in
FIGS. 1 to
9C discloses a single buffer chamber 195a, 195b on each side of the gas
44
CA 2961634 2017-03-20
compressor 150 between the gas compression cylinder 180 and the hydraulic
fluid
chambers 186a, 186b, in other embodiments more than one buffer chamber may be
configured on one or both sides of gas compression cylinder 180. Also, the
buffer
cavities may be pressurized with an inert gas to a pressure that is always
greater
than the pressure of the gas in the gas compression chambers so that if there
is any
gas leakage through the gas piston rod seals, that leakage is directed from
the
buffer chamber(s) toward the gas compression chamber(s) and not in the
opposite
direction. This may ensure that no dangerous gases such as H2S are leaked from
the gas compressor system.
[00150] Various other variations to the foregoing are possible. By way of
example only - instead of having two opposed hydraulic cylinders each being
single
acting but in opposite directions to provide a combined double acting
hydraulic
cylinder powered gas compressor:
- a single but double acting hydraulic cylinder with two adjacent
hydraulic
fluid chambers may be provided with a single buffer chamber located
between the innermost hydraulic fluid chamber and the gas compression
cylinder;
- a single, one way acting hydraulic cylinder with one hydraulic fluid chamber
may be provided with a single buffer chamber located between the hydraulic
fluid chamber and the gas compression cylinder, in which gas in only
compressed in one gas compression chamber when the hydraulic piston of
the hydraulic cylinder is moving on a drive stroke.
[00151] In various other variations a buffer chamber may be provided
adjacent
to a gas compression chamber but a driving fluid chamber may be not
immediately
adjacent to the buffer chamber; one or more other chambers may be interposed
between the driving fluid chamber and the buffer chamber ¨ but the buffer
chamber
still functions to inhibit movement of contaminants out of the gas compression
chamber and in some embodiments may also protect a driving fluid chamber.
CA 2961634 2017-03-20
[00152] In other embodiments, more than one separate buffer chamber
may be
located in series to inhibit gas and contaminants migrating from the gas
compression
chamber.
[00153] One or more buffer chambers may also be used to ensure that a
common piston rod through a gas compression chamber and hydraulic fluid
chamber, which may contain adhered contamination from the gas compressor, is
not
transported into any hydraulic fluid chamber where the hydraulic oil may clean
the
rod. Accumulation of contamination over time into the hydraulic system is
detrimental and thus employment of one or more buffer chambers may assist in
reducing or substantially eliminating such accumulation.
[00154] When introducing elements of the present invention or the
embodiments thereof, the articles "a," "an," "the," and "said" are intended to
mean
that there are one or more of the elements. The terms "comprising,"
"including," and
"having" are intended to be inclusive and mean that there may be additional
elements other than the listed elements.
[00155] Of course, the above described embodiments are intended to be
illustrative only and in no way limiting. The described embodiments of
carrying out
the invention are susceptible to many modifications of form, arrangement of
parts,
details, and order of operation. The invention, therefore, is intended to
encompass
all such modifications within its scope.
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