Note: Descriptions are shown in the official language in which they were submitted.
SYSTEM AND METHOD FOR GENERATING POWER FROM COMPRESSOR
STATIONS
FIELD
[0001] Described herein is a system, method and apparatus for running an
electricity generator
using the engines of compressor stations of natural gas pipelines.
BACKGROUND
[0002] Natural gas is transported from supply areas to centers of consumption
in large gas
pipelines, frequently over distances of several thousand kilometres. These
long-distance gas
pipelines are operated at elevated pressures.
[0003] Unavoidably, there is a loss of pressure along the pipelines over long
distances, because
of friction between the gas and the pipeline wall. Therefore, in order to make
the gas flow
continuously, the gas must be re-pressurized at suitable locations along the
pipeline. This is
accomplished by compressor stations, also known as pumping stations, which are
situated at
intervals along the pipeline, typically about every 80 to 200 kilometres.
These stations
mechanically compress the natural gas to boost its pressure, commonly using
turbines that are
powered by gas taken from the pipeline.
[0004] Because pipelines transporting gas often are thousands of kilometres
long, a number of
compressor stations are needed. The location, size and number of compressor
stations along a
pipeline route is dependent on many factors, including the operating pressure
of the pipeline, the
diameter of the pipe, the volume of gas to be moved, the terrain, and the
number of gas wells in
the vicinity.
[0005] Compressors are designed to operate on a nonstop basis, that is, 24
hours a day 365
days a year; and most are unmanned and monitored offsite. They are
conventionally driven by
engines that have enough horsepower and throughput capacity to exceed
requirements needed to
pressurize the pipeline. Further, reflective of high initial gas reservoir
pressures, pipelines are
commonly initially operated at correspondingly high pressures requiring the
engines to initially
operate at a higher horsepower, but later as pressure in the reservoir and
pipeline decreases, the
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engines will operate at a lower horsepower. Thus, over time compressor
stations have unused
available horsepower which is not needed for pipeline operations. To date,
this available
horsepower has not been recoverable, nor taken advantage of.
SUMMARY
[0006] Disclosed herein is a method and system for generating electricity
using excess
horsepower that is available from an LPG or Diesel engine running at a
pipeline compressor
station. More particularly, the engine drives a compressor that pressurizes
the pipeline, but in
running the compressor the engine is operating at lower than its capacity,
meaning that excess
horsepower is available for other uses. In the method and system described
herein, this excess,
available horsepower is used to drive an electricity generator. The method and
system include a
drive assembly for rotationally coupling the generator and the commonly
incompatible
mechanical output of the engine.
[0007] Because the engine commonly operates at a lower rpm than that needed by
the
generator, the method and system, and more particularly the drive assembly,
may comprise a
means for increasing the rpm of the engine output to the speed needed by the
generator to
generate electricity. Other safety and control mechanisms are included in the
system and method
described herein, to ensure that the operation of the generator does not
compromise the operation
of the compressor.
[0008] Accordingly, in one aspect, described herein is a system for generating
electricity
comprising:
a) an engine of a compressor station;
b) an electricity generator;
c) a rotational coupling between the engine and the generator, said rotational
coupling
comprising:
i) a means for disconnecting the rotational coupling between the engine and
the
generator, and
ii) a soft start device to soft start the generator.
[0009] In embodiments of the system the rotational coupling further comprises
a gear box
having an input shaft that rotates at a first rpm and an output shaft that
rotates at a second rpm
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that is higher than the first rpm. In embodiments the means for disconnecting
the rotational
coupling is a clutch.
[0010] In embodiments of the system the soft start device is a clutch. In
embodiments the
clutch is a fluid driven friction clutch.
[0011] In embodiments the gear box comprises a gear train having a gear ratio
between about
0.44 and 0.72. In embodiments the generator is spaced at least 1 metre from
the engine. In
embodiments the generator is housed in a generator building, and on a
foundation. In
embodiments the foundation is a pile foundation.
[0012] In another aspect, described herein is a system for generating
electricity comprising:
a) an engine of a compressor station in a compressor station building;
b) an electricity generator in a generator building and on a foundation, and
wherein the
generator building is spaced a distance from the compressor station building;
c) a rotational coupling between the engine and the generator, said rotational
coupling
comprising:
i) a fluid driven friction clutch disposed in a gear box;
ii) a drive shaft having a first end and a second end, the first end
connected to a rotating
shaft of the engine and the second end connected to the input shaft of the
gear box;
and
iii) the output shaft of the gear box connected to a rotating shaft of the
generator.
[0013] In embodiments the gear box further comprises an input shaft that
rotates at a first rpm
and an output shaft that rotates at a second rpm that is higher than the first
rpm. In embodiments
the foundation is a pile foundation. In embodiments the drive shaft is about
2.7 metres long.
[0014] In embodiments the system further comprises delivering the electricity
to an electric
power grid. In embodiments the system further comprises electronic controls to
disconnect the
rotational coupling between the engine and the generator.
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[0015] In another aspect, described herein is a method for generating
electricity comprising:
a) identifying a compressor station having an engine that has available
horsepower to drive
an electricity generator;
b) rotationally coupling the engine to the electricity generator;
c) using the available horsepower to drive the generator, by driving the
rotation of a shaft in
the generator with engine; and
d) generating electricity by rotation of the shaft in the generator.
[0016] In embodiments the magnitude of the available horsepower is greater
than about 300
horsepower.
[0017] In embodiments the driving of the rotation of the shaft in the
generator with the engine
can be reversibly coupled and uncoupled. In embodiments the reversible
coupling and
uncoupling is done with a clutch. In embodiments the clutch provides a soft
start for the
generator.
[0018] In embodiments, in using the available horsepower a shaft of the engine
rotates at a first
rpm and the shaft of the generator rotates at a second rpm that is higher than
the first rpm.
[0019] In embodiments the method further comprises disposing a gear train
between the
engine and the generator, said gear train causing the shaft of the generator
to rotate at the second
rpm.
[0020] In embodiments the method further comprises providing electronic
controls to monitor
the compressor to ensure that its rpm remains at or above a threshold value,
and to disengage the
generator from the engine if the rpm of the compressor drops below the
threshold value for
longer than a predetermined time period.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 is a schematic depicting an embodiment of the system described
herein;
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[0022] Figure 2 is a side perspective view of an embodiment of the gear box
used in the method
and system disclosed herein;
[0023] Figure 3 is a side view of the embodiment of Fig. 2;
[0024] Figure 3A is a view taken along a part of a cross section along line A-
A of Fig. 3;
[0025] Figure 4 is an end view of the embodiment of Fig. 2;
[0026] Figure 5A is a plan view of an embodiment of a flexible connection
which attaches the
drive shaft to the engine at one end and the gear reducer; and
[0027] Figure 5B is a cross section along line A-A of Fig. 5A.
DETAILED DESCRIPTION
[0028] Conventionally, natural gas pipelines operate at an initial pressure
that drops over time
as the pressure of the reservoir(s) with which they are associated decreases.
The engines that run
compressors at compressor sites of natural gas pipelines are, therefore,
designed to initially
operate at a high horsepower, but as pressure in the pipeline decreases over
time, they operate at
a fraction of the horsepower for which they are rated. Thus, many engines
associated with
compressor sites are operating well below their design limits and have the
capacity to operate at
higher horsepower. Some estimates are, that for established pipelines, at
least about 300
horsepower, or between about 300 to 900 horsepower (20 to 40% of available
horsepower), are
available from each engine. The system and method described herein relate to
the conversion of
this horsepower into electricity that can be supplied to the electric power
grid.
[0029] As shown in Fig.1, the basic components of the system 10 are an engine
12 that is
connected to a compressor 14 at one (a first) end, and which has the capacity
to operate at a
horsepower that is over and above that needed to drive the compressor 14 to
pressurize the
pipeline. This excess horsepower is sufficient to drive an electricity
generator 16. The engine
and compressor may be housed in an enclosure, such as a building, to protect
them from the
environment.
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[0030] The engine 12 is rotationally coupled at its other (or second) end to
an electricity
generator 16 that is distanced from the engine 12. The engine and generator
are rotationally
coupled by a drive assembly which comprises a soft start device to soft start
the generator, and a
clutch for connecting and disconnecting the rotation of the generator by the
engine. In one
embodiment the drive assembly comprises a drive shaft 18 and a gear box 20
that houses the soft
start device and the clutch. The rotation of the drive shaft 18 is driven by
the engine 12. Because
the rotation speed (rpm) of the engine, and therefore the drive shaft, is
usually lower than the
rpm required by the electricity generator to generate electricity, gear box 20
may further
comprise a gear reducer that converts the lower rotation speed (rpm) of the
drive shaft into a
higher rpm required by the electricity generator. In some embodiments the soft
start device and
clutch are housed separately from the gear reducer. The electricity generator
16 and preferably
also the gear box 20 are housed in a building 22 that comprises a foundation
24, preferably a pile
foundation. In embodiments the gear box comprises a fluid drive friction
clutch.
[0031] The cost of the extra fuel that is required by the engine to operate at
a higher
horsepower is more than compensated for by selling the electricity generated
to the electric
power grid. Moreover, engines being operated at a higher horsepower are
operating closer to
their design rating, improving efficiency and reducing carbon emission
problems that result from
running engines at lower loads.
[0032] In the method and system, an electric generator is driven by an LPG or
diesel engine,
using a rotating drive shaft that extends from one end of the engine to a gear
reducer. The gear
reducer converts the rpm of the shaft into an rpm useable by the generator to
generate electricity.
The generator may be situated in an enclosure (the generator building 22)
which functions to
shield the generator from the environment. The generator building 22 is a
separate structure that
is distanced from the engine, because the heat generated by the engine as it
operates continuously
is significant, particularly in the summer season, and without cooling can be
too high for
operation of the generator close to the engine or within the same building as
the engine and/or
compressor. Further, electronics on the generator that monitor output power to
the electric
power grid are also adversely affected by higher temperatures. In preferred
embodiments the
generator is at least about 1 metre from the engine, more preferably more than
about 3 metres,
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provided that the heat from the engine and compressor can be sufficiently
dissipated so as not to
adversely affect the operation of the generator or its controls.
[0033] Regulations commonly require that a distance of at least about 2.7
metres must be
maintained between the building which houses the engine and compressor, and
any other
building. Accordingly, a in a preferred embodiment the distance between the
engine and
generator is at least about 2.7 metres.
[0034] The generator building 22 may further be insulated to keep the inside
cool, which may
be a concern particularly in the summer season in some locations.
[0035] The generator rests on a foundation 24, optionally on a skid that rests
on the foundation
24. The generator may be enclosed in a building 22, and the top and sides of
the building may be
attached to the foundation or to the skid, for example by welding. The
foundation 24 functions to
transfer vibration loads from the generator to the surrounding soil or rock,
without shifting or
settling, thereby stabilizing the generator and ensuring that it remains
properly aligned with the
engine, as discussed further below.
[0036] Preferably foundation 24 is a pile foundation. A pile foundation is a
deep foundation
formed by long, slender, columnar elements typically made from steel or
reinforced concrete and
sometimes timber. The piles may be end-bearing piles, friction piles or a
combination of both;
they may be driven or screw piles prefabricated off site, bored piles that are
poured in situ, or
continuous flight augured (CFA) piles. The choice of pile will depend on the
location and type of
generator building, the ground conditions, durability of the materials and
cost. Other types of
foundations, such as shallow foundations are contemplated herein, provided
that they provide the
stability required.
10037] As noted above, the distance between the engine 12 and the generator 16
is at least
about 1 metre, and preferably greater. The drive shaft, which extends between
one end of the
engine and the gear box, should remain essentially horizontal over this
distance, meaning that
deviation from horizontal between the two ends of the drive shaft should be
between about 1 to 3
degrees, and not less than about 1 degree. Thus, an important function of the
foundation 22 is
that it supports the generator and the gear box (see below) so that the drive
shaft remains in this
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essentially horizontal position over time. The shaft is maintained in an
essentially horizontal
position to minimize wear on couplings, and deviation from horizontal should
be at least 1
degree to facilitate proper lubrication and movement so that the drive
assembly does not wear in
one spot.
[0038] The drive shaft may be made of metal, such as steel or a steel alloy,
or any other
material, for example carbon fibre, that is suitable for the intended use of
the drive shaft in
accordance with this disclosure.
[0039] In preferred embodiments the distance between the engine and the
generator is at least
about 3 metres and may be much longer than that. In a particularly preferred
embodiment the
drive shaft, which extends between the engine and the gear box is about 2.7
metres long, or
longer. While the system and apparatus described herein contemplate a distance
between the
engine and compressor of as little as 1 metre, in preferred embodiments this
distance is longer.
More particularly, it may be desirable to have a distance of at least 1 metre
between the engine
and the gear box (gear reducer) to facilitate the uncoupling of the drive
assembly from the
compressor engine, and another 0.5 metres between the gear box (gear reducer)
and the generator
to facilitate maintenance on both the gear reducer and the generator.
[0040] The generator 16 used in the systems and methods herein converts the
rotational
(mechanical) energy of the drive shaft extending from the engine, to
electrical energy that is
preferably delivered to the electric power grid, however it may be delivered
optionally or in
addition to a battery where it is stored for future use, or it may be used to
provide power to an
isolated site. The type of generator used will be determined by the
requirements of the electric
power grid to which the generator will be connected, provided that it converts
rotational
(mechanical) energy into electricity.
10041] The generator may be selected to provide an electrical output at a
fixed frequency of
about 60 Hz to match the output of a standard electric power grid in North
America, or at about
50 Hz for Europe. Generators commonly operate at 1800 rpm, however they can be
designed to
operate at other rpms, and these other generators are intended to be included
herein.
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[0042] Engines 12 that run compressors at compressor stations generally rotate
at a revolution
per minute (rpm) which is lower than the rpm required by a power generator to
generate
electricity. Thus, for example, many engines rotate at about 1100 or 1150 rpm,
lower than the
about 1800 rpm required for a standard power generator to operate.
Accordingly, contemplated
herein in some embodiments of the drive assembly is a gear reducer that
converts the speed
(rpm) of the rotating drive shaft at the input side of the gear box to an
increased speed (rpm) at
the output side of the gear box, as required by the generator.
[0043] In preferred embodiments gear reducer is housed in gear box 20. Gear
box 20 may
therefore comprise a gear train in a casing, which gear train functions to
increase the rate of
rotation of the output (driven) shaft over that of the input shaft (driver)
shaft. The "gear ratio",
as defined herein is the ratio of the input speed (driver) relative to the
output speed (driven):
win:wout= As the speed (rpm) of the shaft at the input of the gear box is less
than the speed (rpm)
of the shaft extending from the output of the gear box, the gear ratio of the
gear box 20
contemplated herein is less than 1.
[0044] The gear train can be any type of gear train, for example a simple gear
train, a
compound (including variable) gear train, a reverted gear train or a planetary
(epicyclic) gear
train, as are known in the art. The arrangement of the gear train depends upon
the speed increase
desired, the orientation of the input and the output shafts, and the size of
the gear box. In some
embodiments, a 90 degree speed increaser, for example a device similar to R.
J. Link
International's right angle speed increaser 1:1.57 may be used. While the gear
box has at least
one gear train that provides at least one gear ratio that is less than 1,
embodiments contemplate a
variable gear train that provides a plurality of different gear ratios that
are less than one, and the
desired gear ratio can then be selected depending on the rpm of the specific
engine and/or the
rpm of the specific generator to be used.
[0045] A preferred gear ratio range for the gear train described herein is
between about 0.44
and 0.72, used when the rpm of the engine is between 800 and 1300 rpm and the
rpm required
for the generator is about 1800 rpm. A particularly preferred embodiment has a
gear ratio of
between 0.61 and 0.64, used when the rpm of the engine is between 1100 and
1150 rpm and the
rpm for the generator is about 1800.
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[0046] In embodiments the engine 12 and generator 16 rotate at essentially the
same rpm and it
is not necessary for the rpm to be increased between the engine and generator.
These
embodiments therefore do not include a gear reducer in the drive assembly.
[0047] Gear box 20 is operated by at least one clutch which connects (engages)
and
disconnects (disengages) the input and output shafts of the gear box; thus
connecting and
disconnecting the rotation of the engine from the rotation of the generator.
Electronic controls
may be used to engage and disengage the clutch. The use of a clutch enables an
operator to
disconnect the generator when not needed (for example, to turn it off when the
grid does not
need electrical power) without needing to turn off the engine. Further, the
ability to disconnect
the engine from the generator ensures that if operation of the generator were
to somehow
compromise the operation of the engine, the generator can be disconnected to
allow for
continued operation of the engine and consequently the compressor, to maintain
pressure in the
pipeline.
[0048] The gear box 20 can comprise any of a number of different types of
clutches, and may
have one or more clutches. The clutches may be manual or automatic; wet or
dry; dog, friction
or hydraulic; single plate, multi plate, cone or diaphragm; fluid; spring,
centrifugal,
electromagnetic, for example. Preferred for use herein is a fluid driven
friction clutch.
[0049] Engines at compression stations operate continuously, and at only one
speed, thus it is
not practical to bring the generator up to speed by gradually increasing the
rpm of the engine.
'Therefore, preferred embodiments of the system and method described herein
include a soft start
device that provides for a smooth, controlled acceleration of the generator to
its steady state rpm;
this in turn gradually increases the load and torque on the engine and reduces
mechanical stresses
on the engine and generator. The soft start avoids damage to the engine or
compressor, or
stalling of the engine, which might otherwise occur were the generator to
immediately go from
zero rpm to full operating speed.
10050] The soft start can consist of a mechanical or electrical device, or a
combination of both;
however mechanical soft start devices are preferred. Mechanical soft starter
devices include
clutches and several types of couplings using a fluid, magnetic forces, or
steel shot to transmit
CA 2978788 2017-09-11
torque, similar to other forms of torque limiter. Electrical soft starters can
be any control system
that reduces the torque by temporarily reducing the voltage or current input.
[0051] Preferred in embodiments herein is a mechanical soft start device, as
the system and
method described herein are commonly used in remote locations where electronic
controls and
drives are difficult to power, program, and maintain. Mechanical soft starters
are well known in
the art and are manufactured and sold, for example by Dodge or Twin Disk .
[0052] Of mechanical soft start devices, preferred is a fluid driven friction
clutch, which
connects and disconnects the input and output shafts of the gear box and which
also provides a
soft start, bringing the generator up to the required rpm within a specified
period of time, and
locking after the required rpm is attained. Clutch engagement does not occur
instantaneously but
takes place over time due to a gradual pressure increase in the actuating
chamber. Such clutches
have been described, for example, in US Patent No. 5,651,288, which is
incorporated herein by
reference in its entirety. An embodiment of the clutch is shown in Figs. 2 to
4.
[0053] Another type of mechanical clutch is a clutch having a fluid coupling,
which generally
consists of a housing which contains hydraulic fluid and two bladed rotors
with radial vanes, one
an impellor connected to the input shaft and the other a runner connected to
the output shaft. The
input shaft rotates the impellor, which in turn accelerates the hydraulic
fluid; this fluid with
increased kinetic energy impinges on the runner, which reacts as a turbine
rotating the output
shaft. The hydraulic fluid may be motor oil. A clutch with a fluid coupling
has lower efficiency
than a fluid driven friction clutch, and there is a greater risk of oil spills
and leaks when using
these types of hydraulic systems. The amount of oil to operate a fluid driven
friction clutch
according to an embodiment described herein is less < 20 L.
[0054] In embodiments, the system is configured to reduce torsional vibration
along the drive
shaft, which can harm the engine. Accordingly, flexible or antivibration
mountings which
absorb the vibration, such as rubber mounted couplings, may be used where the
drive shaft exits
the building around the engine, and where the drive shaft enters the generator
building. Further,
the drive shaft may be mounted to the housing of the gear box and to the
engine via rubber
mountings. An embodiment of the antivibration coupling that may be used at the
gear box and
the engine is shown in Figs. 5 A and B.
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[0055] Embodiments may also include a means to mechanically disconnect the
drive shaft
from the engine and/or generator, to eliminate any possibility of an
accidental start while
working on any component of the system ¨ e.g., the engine, the drive or the
generator. This
disconnection means may be a slip joint on the drive assembly which enables
the drive assembly
to be uncoupled mechanically.
[0056] In embodiments the operation of the gear box (drive) is remotely
monitored and
controlled by a SCADA system (Supervisory Control and Data Acquisition),
providing operators
for the electric power grid with the capability of connecting the generator to
the electric power
grid to acquire the electricity generated, as well as to disconnect the
generator when power is not
required.
[0057] Embodiments include and under- and over-frequency relays for the
generator. The
under-frequency relay may ensure that the generator is brought up to speed
before engaging the
electric power grid, for otherwise the power generated will be under frequency
and under
voltage. Electronic controls may initiate the generator when its output is
appropriate for
connection to the electric power grid.
[0058] The electrical output of the generator may be maintained at a fixed
frequency of about
60 Hz to match the output of a standard electric power grid in North America,
or at about 50 Hz
in Europe. Accordingly, the system and method may include under- and over-
frequency controls
to maintain the frequency within a desired range, shutting the generator down
(i.e., disengaging
the clutch) if the frequency is outside of that range. For use in North
America the system may
include controls for maintaining the frequency between about 59.6 and 60.1 Hz,
shutting down if
frequency is below about 59.4 Hz or above about 61 Hz. The generator may
include a number of
relays that control the electrical output including: fault, phase imbalance
and ground faults.
[0059] Further embodiments include controls to ensure that the operation of
the generator does
not compromise operation of the compressor. Therefore, electronic controls are
provided so that
if there is a possibility that the generator will compromise the operation of
the compressor, it is
disconnected from the engine. For example, engines of conventional compressor
stations run
constantly and at a constant rpm. If the rpm decreases, conventional
electronic controls will stop
the engine if rpm is not back up to the required rpm within a specified time,
for example, 30
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seconds. In the system and method described herein, when the generator is
started up, any
consequent reduction in the rpm of the engine must be remedied before the 30
seconds has
passed, to avoid shut down of the engine. Controls are therefore provided to
shut the generator
off (i.e., disconnect the clutch) before this might happen.
METHOD
[0060] In the method, an engine is selected to run at a specific first rpm,
and when the engine
is coupled at one end to a compressor, the compressor will maintain the
pipeline at a specified
pressure. The rpm of the engine and the pipeline pressure are monitored and
controlled, as
known in the art.
[0061] At the first rpm, the engine is operating below capacity, that is,
below its maximum
horsepower rating. Thus, the engine has excess capacity and has enough
available horsepower to
drive an electricity generator, when operating at the first rpm.
[0062] An electricity generator which is capable of generating electricity at
a second rpm that
may be higher than the first rpm, is selected. The generator is housed in a
building and on a
stable foundation, and is distanced from engine because heat from the engine
and/or compressor
may compromise the operation of the generator or its controls.
[0063] The engine and the generator are releasably and rotationally coupled,
so that the
rotation of a shaft within the engine at the first rpm drives the rotation of
a shaft within the
generator at the second rpm. The rotational coupling may include a means for
converting the first
rpm of the shaft within the engine to the second higher rpm of the shaft of
the generator. In an
embodiment, rotational coupling is accomplished by a combination of a drive
shaft and a gear
box; the engine rotates the drive shaft at the first rpm, the gear box
increases the rpm to the
second rpm required by the generator, and then causes the shaft of the
generator to rotate at the
second rpm.
[0064] In preferred embodiments the rotational coupling includes means to soft
start the
generator, so that the ramp up to operating speed is gradual, avoiding damage
to the generator or
engine, or avoiding stalling the engine.
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[0065] In preferred embodiments the gear box includes a reversible connection
means, such as
a clutch, so that the engine and the compressor can be rotationally connected
and disconnected as
needed. An ability to disconnect may be needed, for example, if an operator
desires to turn off or
generator for maintenance or because the power is not needed for the grid, or
if the operation of
the generator compromises, or is at a risk of compromising, the ability of the
engine to operate
the compressor.
[0066] Having thus described the basic system and method herein, a specific
embodiment will
now be described, as shown in the accompanying Figures.
[0067] Figs. 2 to 4 are drawings of an embodiment of the gear box used in the
method and
systems herein. The gear box is a modified TwinDisc transmission used in
marine
applications, that has fluid flow and gearing optimized for use in the systems
and methods
herein. More particularly, in this embodiment the gear box comprises a fluid
drive friction clutch
and has a gear train that converts an input rpm of 1150 from the engine to an
output rpm of 1800
for running the generator. The clutch is a wet clutch, and comprises stacking
multiple clutch
discs immersed in a lubricating fluid (motor oil).
[0068] In the embodiment shown in Figs. 2 to 4, the axis of rotation of the
output shaft is
shown by dashed line 26, and the axis of rotation of the input shaft is shown
by dashed line 28.
[0069] In an embodiment, the drive shaft is 2.7 metres long, having a diameter
of about 3", and
is made of tubular steel.
[0070] Embodiments of engines for use herein are Gas compression engines Cat
G3516TM and
the Wakesha L7O44GSITM. These are typically 1400 and 1600 horsepower engines
that run on
natural gas.
[0071] Embodiments of the generators contemplated are the synchronous
type, continuous
duty, dual bearing (for longer maintenance times) generators rated at 385 kVA,
425 kVA or 700
kVA, having a moment of inertia of 4.02/4.04 kg-m2, 5.19/5.20 kg-m2, and 10.47
k-gm2,
respectively. The clutch was designed taking into account the torque required
to start the
generator, the engine speed and the available horsepower from the engine.
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[0072] Figs. 5A and 5B are drawings of an embodiment of a coupling 30
that may be
used to couple the drive shaft to a rotating shaft of the engine or to the
input shaft of the gear
box, or to couple the output shaft of the gear box to the rotating shaft of
the generator. The
coupling comprises a splined rubber insert 32 (e.g., as made by Lovejoy or
Reich ) as an
antivibration material, and tapered bushings with splines.
[0073] While the system and method have been described in conjunction
with the
disclosed embodiments which are set forth in detail, it should be understood
that this is by
illustration only and the method and system are not intended to be limited to
these embodiments.
On the contrary, this disclosure is intended to cover alternatives,
modifications, and equivalents
which will become apparent to those skilled in the art in view of this
disclosure.
CA 2978788 2017-09-11
