Note: Descriptions are shown in the official language in which they were submitted.
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USE OF REFRIGERATION LOOPS TO CHILL INLET MR TO GAS
TURBINE
[0001] This application is co-pending to U.S. Patent Application
entitled
"Method to Maximize LNG Plant Capacity in All Seasons", filed 30 December
2010,
Attorney Docket No. 70205.0221US01, the contents of which are herein
incorporated by
reference in their entirety.
Field of the Invention
[0002] The present application relates to a method and system which
maximizes
gas turbine output for a refrigerant loop. The method consumes a small amount
of
refrigerant and utilizes the refrigeration to chill the inlet air to the gas
turbine ((iT)
machines used in the refrigeration system. This approach enhances the gas
turbine
power output and efficiency which, in turn, increases the production of the
plant. The
gain in efficiency in production can compensate for the consumption of
refrigerant.
Backuround of the Invention
[0003] Gas turbines are commonly used for driving compressors in
refrigeration
systems. For example, gas turbines are used in to drive refrigeration
compressors in
LNG production, air separation, food storage and ice making.
[0004] Gas turbines are constant volume machines and their output
depends on
the mass flow of air through the turbine. Over the years various technologies
have been
developed to increase the amount of useful power that gas turbines are able to
produce.
One way of increasing the power output of a gas turbine is to cool the turbine
inlet air
prior to compressing it in the compressor. Cooling inlet air increases the air
mass flow
through the turbine, increasing turbine output and reducing heat rate. Cooling
the inlet
air also increases the turbine's efficiency.
[0005] Degradation of gas turbine output power with a rise in ambient
air
temperature further poses a serious problem. Cooling inlet air can address the
problems
associated with rising ambient temperatures.
[0006] Various systems have been devised for chilling the inlet air.
One system
uses evaporative cooling, another uses a chiller to chill water that is then
run through a
coil. However, a continuing need exists for a turbine inlet air cooling system
and method
which is efficient and does not drain the system of power.
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Summary of the Invention
100071 As described herein, a method and system for maximizing gas
turbine
output for a refrigeration loop are provided. The method and system provide a
gain in
energy efficiency of the gas turbine while compensating for an amount of
energy
required for consuming a portion of refrigerant.
100081 In one embodiment disclosed herein is an integrated system for
refrigeration. The system comprises (a) a refrigeration system comprising a
refrigeration
loop for air-chilling; (b) a gas turbine for driving a compressor for the
refrigeration
system; (c) a heat exchanger for consuming a portion of refrigerant from the
refrigeration
system and cooling a heat transfer fluid; and (d) a second heat exchanger for
reducing the
temperature of inlet air entering the gas turbine with the heat transfer
fluid.
[00091 In another embodiment disclosed herein is an integrated method
of
maximizing gas turbine output for a refrigeration loop. The method comprises
(a)
operating a refrigeration loop for chilling processes; (b) operating a gas
turbine to drive a
compressor for a the refrigeration loop; (c) gasifying a portion of
refrigerant from the
refrigeration system; and (d) reducing the temperature of inlet air entering
the gas
turbines by exchanging heat with the gasified portion of refrigerant either
directly or
indirectly.
[000101 In an additional embodiment disclosed herein is an integrated
method of
operating a gas turbine used in a refrigeration loop. The method comprises (a)
operating
a gas turbine to drive a compressor for a refrigeration system comprising a
refrigeration
loop and (b) chilling inlet air entering the gas turbine by (i) exchanging
heat with a
refrigerant in the refrigeration loop; or (ii) cooling a heat transfer fluid
with a refrigerant
in the refrigeration loop, and chilling inlet air entering the gas turbine by
exchanging heat
with the heat transfer fluid; or both (i) and (ii). In the method the
refrigerant in the
refrigeration loop comprises methane, ethane, propane, ammonia, a
hydrofluorocarbon, a
chlorofluorocarbon, a hydrochlorofluorocarbon, a bromofluorocarbon, a
bromochlorofluorocarbon, or any combination thereof; and the heat transfer
fluid
comprises methanol, ethanol, a glycol and water mixture, or any combination
thereof. In
this method the gas turbine and refrigeration system can be used to produce
LNG and the
method further comprises cooling and condensing a natural gas stream by
reducing the
temperature of the natural gas using the refrigeration system.
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1000111 In another embodiment disclosed herein is an integrated
liquefied natural
gas (LNG) system. The system comprises (a) an inlet stream comprising natural
gas; (b)
a refrigeration system for reducing the temperature of the natural gas and
condensing the
natural gas to produce LNG; (c) a gas turbine for driving a compressor for the
refrigeration system; (d) a first vaporization heat exchanger for regasifying
a portion of
the LNG and cooling a heat transfer fluid; (e) a second vaporization heat
exchanger for
consuming a portion of refrigerant from the refrigeration system and cooling
the heat
transfer fluid; and (f) a third heat exchanger for reducing the temperature of
inlet air
entering the gas turbine with the heat transfer fluid. The integrated system
can further
comprise an outlet pipeline for supplying the regasified portion of the LNG to
the
domestic gas market.
[000121 In a further embodiment discloses herein is an integrated
method for
operating a liquefied natural gas (LNG) plant, the method comprising: (i)
cooling and
condensing a natural gas stream. in a refrigeration system to produce
liquefied natural gas
(LNG); (ii) operating a gas turbine to drive a compressor for the
refrigeration system;
(iii) regasifying a portion of the LNG; (iv) consuming a portion of the
refrigerant from
the refrigeration system; and (iv) reducing the temperature of inlet air
entering the gas
turbine by exchanging heat with the regasified portion of the LNG and with the
consumed portion of the refrigerant directly or indirectly.
Brief Description of the Drawines
1000131 Figure 1 illustrates an embodiment of the proposed
refrigeration loop.
[OHM Figure 2 is a graph showing the monthly temperature variations
at three
locations for LNG and domestic natural gas production.
Detailed Description of the Invention
100151 In the prc-:c.rit methods and systems, a portion of refrigerant
from the
refrigeration system is utilized to cool the inlet air to the gas turbines in
the refrigeration
system, either directly or indirectly.
Definitions
PON In accordance with this detailed description, the following
abbreviations
and definitions apply. It must be noted that as used herein, the singular
forms "a", "an",
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and "the" include plural referents unless the context clearly dictates
otherwise. Thus, for
example, reference to "gas turbine" includes a plurality of such.
[00017] Unless otherwise stated, the following terms used in the
specification and
claims have the meanings given below:
[00018] "LNG" is liquefied natural gas. Natural gas from the well can
consist of
various hydrocarbons and contaminants; natural gas for the domestic market is
comprised primarily of methane. At ambient temperature and pressure, LNG
exists as a
gas, but it can be cooled and/or pressurized to provide a liquid, which
facilitates storage
and transportation.
[00019] "Remote location or market" means a location that is not
readily
accessible or economically feasible to access by pipeline. For example, a
remote
location or market can be at least over a thousand miles away from the natural
gas source
and/or is separated in geography such that it is not accessible by pipeline,
for example,
separated by oceans or other large, deep bodies of water.
[000201 "Local market" means a location that is within a distance and
geography
from the natural gas source so that the natural gas may be supplied as a gas
by pipeline.
For example, local markets can be at any distance within several thousand
miles from the
natural gas source and is accessible by pipeline.
[00021] "Direct" in the context of heat exchange means that the heat
exchange
between the refrigerant and the inlet air is direct with no intermediate heat
transfer fluid
involved.
1000221 "Indirect" in the context of heat exchange means that the heat
exchange
between the refrigerant and the inlet air involves an intermediate heat
transfer fluid.
Accordingly, the temperature of inlet air entering the gas turbine is reduced
by
exchanging heat with the refrigerant through a heat transfer fluid system.
[00023] "Integrated" means that the steps or units of the system or
interconnected
so that when operating together greater efficiencies are realized in
comparison to when
operating independently.
1000241 A "hydrofluorocarbon" means a compound containing carbon,
hydrogen,
and fluorine.
[00025] A "chlorofluorocarbon" means a compound containing carbon,
hydrogen,
fluorine, and chlorine.
[00026] A "bromofluorocarbon" means a compound containing carbon,
hydrogen,
fluorine, and bromine.
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1000271 A bromochlorofluorcarbon means a compound containing carbon,
hydrogen, fluorine, bromine, and chlorine.
100028i "Substantially all" means at least 90 % and up to 100 %.
1000291 "Optional" or "optionally" means that the subsequently described
event or
circumstance may, but need not, occur, and that the description includes
instances where
the event or circumstance occurs and instances in which it does not.
[00030] Most refrigeration systems utilize one or more gas turbines to
drive the
refrigeration compressors. Power generators are also driven by gas turbines in
refrigeration systems. The combined output and efficiency of all gas turbines
determines
the total capacity of the refrigeration system. Refrigeration systems driven
by one or
more gas turbines are utilized in LNG production, air separation, food
storage, and ice-
making.
[00031] For example, LNG plants utilize one or more gas turbines to
drive the
refrigeration compressors required to liquefy the natural gas and power
generators are
also driven by gas turbines in the LNG plants. In LNG plants, a portion of the
natural
gas collected may also be utilized as a fuel for power generation for the LNG
plant,
including for the gas turbines. The combined output and efficiency of all gas
turbines
determines the total capacity of the LNG plant.
[00032] The present application provides a method and a system which
maximizes
refrigeration systems driven by gas turbines in all seasons. In the present
methods and
systems substantially a small portion of refrigerant from the refrigeration
system is
consumed and the cooling from this process is used to reduce the temperature
of inlet air
entering gas turbines of the refrigeration system. The portion of refrigerant
utilized for
cooling the inlet air may be recycled to the refrigeration system.
[00033] Accordingly, with the present method and system, integration is
utilized
to increase the gas turbine power output and to efficiently provide
refrigeration. Thus,
the present method and system provide a gain in the efficiency in the
refrigeration
system operated by gas turbines.
[00034] One embodiment of the present method and system relates to LNG
production and the refrigeration facility is a LNG liquefaction plant. In LNG
methods
and systems, natural gas is produced from a field or well. The produced supply
of
natural gas is collected. The LNG liquefaction plant is utilized to process
substantially
all of the natural gas stream. The inlet air to the gas turbines can be
chilled with a
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portion of refrigerant from the refrigeration system. Optionally, the inlet
air to the gas
turbines can also be cooled with a portion of LNG, which is regasified.
1000351 in the present methods and systems, the effect of monthly
temperature
variation of the location on the capacity of the refrigeration facility is
stabilized. The
capacity of the refrigeration facility can be sensitive to environmental
temperature
variation. The capacity of the refrigeration facility is determined by the
total output of
the gas turbine machines in the refrigeration system and it is challenging to
maintain the
power output at a stable and maximum level.
1000361 According to the present methods and system, it has been
surprisingly
discovered that consuming a portion of the refrigerant from the refrigeration
system and
using the cooling effect to cool the inlet air for the gas turbines can
maintain the power
output of the facility at a stable and maximum level. By making inlet air to
gas turbines
stable and constant throughout the entire year, the plant (or capital)
utilization efficiency
is also greatly improved. The gain in energy efficiency by reducing the
temperature of
the inlet air entering the gas turbines can compensate for the consumption of
refrigerant.
The optimal degrees of chilling are machine-specific.
1000371 The refrigeration system comprises a refrigeration loop. The
refrigeration
system can comprise a single stage or multi stage refrigeration loop. For
example, the
multistage refrigeration loop can be a two stage, three stage or four stage
loop. In one
embodiment, the refrigeration system comprises a two or three stage
refrigeration loop.
When a multistage refrigeration loop is used, the consumed portion of
refrigerant can
come from the first stage of the refrigeration loop.
1000381 The refrigerant used in the refrigeration system can be any
suitable
refrigerant. Suitable refrigerants include methane, ethane, propane, ammonia,
a
hydrofluorocarbon, a chlorofluorocarbon, a hydrochlorofluorocarbon, a
bromofluorocarbon, a bromochlorofluorcarbon, or any combination thereof
[000391 The heat transfer can be indirect and involve the use of a heat
transfer
fluid. Any suitable heat transfer fluids can be used. Suitable heat transfer
fluids include
methanol, ethanol, a glycol and water mixture, or any combination thereof.
1000401 In one embodiment the refrigerant is propane and the heat
transfer fluid is
methanol.
1000411 The heat transfer can be either direct or indirect. The inlet
air entering the
gas turbine can be chilled by exchanging heat with a refrigerant in the
refrigeration loop.
The inlet air can be chilled by exchanging heat with a heat transfer fluid,
which has been
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cooled by exchanging heat with a refrigerant in the refrigeration loop. The
inlet air can
also be chilled by both.
100042] in one embodiment, the temperature of the inlet air entering
the gas
turbines can be reduced by 10 to 4017 from the ambient temperature of the
refrigeration
system. In an embodiment, the temperature of the inlet air entering the gas
turbines can
be reduced by at least 20 F from the ambient temperature. In another
embodiment, the
temperature of the inlet air entering the gas turbines can be reduced to a
temperature in a
range of from about 40 to 55 F or 45 to 55 'F. In an additional embodiment,
the
temperature of the inlet air entering the gas turbine can be reduced from an
ambient
temperature in a range of from about 60 to about 120 F to a temperature in a
range of
from about 45 to about 55 F. In a further embodiment, the temperature of the
inlet air
entering the gas turbine can be reduced from an ambient temperature in a range
of from
about 80 to about 120 F to a temperature in a range of from about 42 to about
60 "F.
1000431 In one embodiment, the efficiency of the gas turbines is
increased by at
least 3 %. The efficiency may be increased by at least 3 % by reducing the
temperature
of the inlet air from an ambient temperature of 90 F to a temperature of 50 F.
100044] By maintaining the inlet air for the gas turbines at a constant
low
temperature, the amount of power generated by the turbine remains high
regardless of the
ambient air temperature. By carefully regulating the refrigerant to be
consumed for
cooling, it is possible to control the refrigeration supply and maintain the
inlet air to a gas
turbine at a cool and stable level. Thus, the gas turbine output and
efficiency can be
maximized in all seasons and in all climates.
1000451 For facilities in tropical regions that have high average
temperatures,
which relatively stable, the present system and methods can be utilized to
lower the
average values to maximize turbine output. In the Arctic with low temperatures
and
large seasonal variations, the present system and methods can be utilized to
mitigate the
seasonal variations. In the desert with high average temperatures and large
seasonal
variation, the present system and methods can be utilized to lower the average
temperature and maintain the stability of the temperature. Figure 2 is a graph
showing
the monthly temperature variations at three locations. The portion of the
refrigerant to be
consumed is utilized to control the inlet air temperature and maintain the
power output at
a steady, maximum level. Therefore, facilities for refrigeration, including
facilities for
LNG production, can be built at a variety of locations without concern that
the ambient
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air temperatures will affect the efficiency. During cold seasons or climates,
the air
conditioning requirement provided by the consumed refrigerant is reduced.
[000361 The gain in gas turbine output and efficiency can compensate
for cost for
the additional refrigerant that is consumed. The gain may be measured over the
seasonal
variations for climates with cold seasons and the additional production during
colder
seasons can be used to compensate for the additional energy required for
initial
refrigeration durin.g wanner seasons.
1000471 One embodiment of the method and system is illustrated in
Figure 1. A
refrigeration system is provided for air-chilling. The refrigeration system
comprises a
two stage refrigeration loop. A gas turbine drives a compressor for the
refrigeration
system. In the system, a portion of refrigerant is consumed and used for
cooling the inlet
air entering the gas turbine of the refrigeration system. The refrigerant can
cool the inlet
air either directly or indirectly through the use of an intermediate heat
transfer fluid.
1000481 In one embodiment a heat exchanger transfers heat from the
portion of
refrigerant to be consumed and cools an intermediate heat transfer fluid. A
second heat
transfer exchanger exchanges heat from the intermediate heat transfer fluid
and reduces
the temperature of inlet air entering the gas turbine. The second heat
exchanger can
comprise a cooling coil at an inlet of the gas turbine.
[00049] In one embodiment, the portion of refrigerant to be consumed is
withdrawn from the first refrigeration loop. The portion of refrigerant to be
consumed
can be in a range of from 5 to 25% by weight of the total refrigerant. In one
embodiment
the portion of refrigerant to be consumed can be in a range of from about 10
to 25% by
weight of the total refrigerant.
1000501 The refrigerant prior to reducing the temperature of the inlet
air can be at
a temperature of about -45 to about 45 F. In another embodiment, the
refrigerant prior to
reducing the temperature of the inlet air can be at a temperature of about -45
to about
30 F. When an intermediate heat transfer fluid is utilized for indirect heat
transfer, the
temperature of the heat transfer fluid prior to reducing the temperature of
the inlet air can
be at a temperature of about -45 to about 30 F. In another embodiment, the
temperature
of the heat transfer fluid prior to reducing the temperature of the inlet air
can be at a
temperature of about -45 to about 0 F. In a two stage refrigeration loop, the
temperature
of the refrigerant in the second loop can be in the range of about -100 to
about 0 F.
[00051] After the cooling is complete, at least a portion of the
consumed
refrigerant can be recycled back to the refrigeration loop if desired.
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1000521 The gas turbine of the refrigeration compressors condenses
water vapor
from the ambient air of the facility. The power generator for the facility may
also
condense water vapor from the ambient air. This condensed water is distilled
quality
water. Accordingly, the condensed water can be collected and used for other
uses in the
plant. For example, it can be used for wet compression, evaporative cooling,
and/or
fogging the inlet air to the gas turbines. The water can be used as plant
process water
such as hydrogen sulfide removal by passing natural gas through water or amine
based
solution. The water can be used for compressor circulation cooling and inlet
humidity
adjustment. Because it is distilled quality water, it can also be used for any
use for which
distilled water may be needed in the area of the plant. For example, it can be
used as a
source for drinking water or irrigation water as well. A source for drinking
water or
irrigation water may be particularly useful in desert locations.
[00053] The gas turbine according to the methods and systems described
herein
can be used to drive a compressor in the refrigeration system. The gas turbine
can also
be used to drive a steam generator or can be configured to generate
electricity.
Refrigeration systems driven by the one or more gas turbines can be utilized
in LNG
production, air separation, food storage, and ice-making.
[000541 In one embodiment, the presently claimed integrated
refrigeration system
and method can be used in a liquefied natural gas system. The liquefied
natural gas
system can have addition integration for chilling the inlet air of the gas
turbines. Such an
integrated LNG system and method are described in U.S. Patent Application
entitled
"Method to Maximize LNG Plant Capacity", filed 30 December 2010, Attorney
Docket
No. 70205.022 ISO!, the contents of which are herein incorporated by reference
in their
entirety. In this integrated liquefied natural gas system, natural gas is
produced from a
field or well and the produced supply of natural gas is collected as an inlet
stream.
[00055] The inlet stream of natural gas is fed to a refrigeration
system for reducing
the temperature of the natural gas and condensing the natural gas to produce
LNG (a
liquefaction and refrigeration unit. The refrigeration system may be a single
stage or
multistage stage refrigeration loop. One or more gas turbines drive a
compressor for the
refrigeration system.
1000561 The liquefied product is then sent to a storage tank. From the
storage
tank, LNG can be collected to ship or transport to a remote market.
[00057] According to the integrated LNG system and method, a portion of
the
LNG is taken from the collection/storage tank for regasification. The portion
of LNG is
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regasified in a regasification unit. The portion of the LNG to be regasified
can be in the
range of from 5% to 25% by weight of the total LNG produced. In another
embodiment,
the portion of the LNG to be regasified can be in the range of from 10% to 20%
by
weight of the total LNG produced. The regasification unit can be a
vaporization heat
exchanger for regasifying the portion of the LNG and cooling a heat transfer
fluid. The
heat transfer fluid can comprise methanol, ethanol, propane, an ethylene
glycol and water
mixture or any combination thereof. The heat transfer fluid can also take
additional heat
or refrigeration from auxiliary sources.
1000581 in the present methods and system, the heat transfer fluid
takes additional
refrigeration from the refrigeration loop comprising refrigerant. A second
vaporization
heat exchanger is present for consuming a portion of the refrigerant of the
refrigeration
loop and further cooling the heat transfer fluid.
[000591 A third heat exchanger is utilized for reducing the temperature
of inlet air
entering the gas turbine with the heat transfer fluid. This heat exchanger can
comprise a
cooling coil at an inlet of the gas turbine.
[000601 Thus, the portion of LNG to be regasified and the refrigerant
to be
consumed releases refrigeration and this is used to reduce the temperature of
inlet air
entering gas turbines of the refrigeration system in the LNG plant either
directly or
indirectly. As such, the temperature of inlet air is reduced by exchanging
heat either
directly or indirectly with the regasified portion of the LNG and the
refrigerant. In one
embodiment, the heat is exchanged indirectly through the use of an
intermediate heat
transfer fluid.
1000611 In this integrated LNG method and system, the regasified
portion of
LNG can be supplied to an outlet pipeline for supplying the regasified LNG to
the
domestic gas market.
[000621 The regasified LNG can be supplied to a natural gas pipeline
for domestic
or local natural gas production. By taking the inlet natural gas stream and
creating LNG
and then using the regasified LNG as the stream for the local natural gas
market, the
natural gas stream for the local market has any contaminants removed by the
LNG
process. Therefore, a separate facility is not required to remove
contaminants, such as
sulfur and carbon dioxide, from the natural gas before providing it to the
domestic
energy market.
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1000631 If the regasified portion of the LNG is not needed for domestic
natural gas
production, or it is not all needed, the regasified LNG, or a portion of the
regasified
LNG, can be recycled to the refrigeration system to provide LNG.
[000641 The regasified LNG does not require an additional separate
cleaning
facility prior to use as domestic natural gas because it is cleaned
sufficiently in the
liquefaction process. Accordingly, the regasified portion of the LNG can be
exported
directly by pipeline for use in a local or domestic natural gas market.
Because the
regasified LNG has substantially all contaminants removed by the LNG process,
the
regasified LNG is cleaner than natural gas typically recovered for local or
domestic
market production. Natural gas recovered for local or domestic market
production is
processed to remove contaminants, such as sulfur and carbon dioxide, to meet
pipeline
specifications.
[00065] The regasified LNG can also be used to blend with natural gas
directly
collected for domestic production to meet pipeline specifications. When the
regasified
LNG is blended with natural gas, the natural gas can be processed less
severely removing
fewer contaminants so that the natural gas alone would not meet pipeline
specifications.
But the blend can meet pipeline specifications. The regasified LNG can be
blended with
natural gas, which has been not processed or has been processed less severely,
and the
blend meets pipeline specifications. For example, in cooler seasons it may be
possible to
blend high purity, regasified LNG with unprocessed or less processed natural
gas and
meet pipeline specifications for domestic gas production.
[000661 The gas turbine of the refrigeration compressors condenses
water vapor
from the ambient air of the facility. The power generator for the LNG plant
may also
condense water vapor from the ambient air. This condensed water is distilled
quality
water. Accordingly, the condensed water can be collected and used for other
uses in the
plant. For example, it can be used for wet compression, evaporative cooling,
and/or
fogging the inlet air to the gas turbines. The water can be used as plant
process water
such as hydrogen sulfide removal by passing natural gas through water or amine
based
solution. The water can be used for compressor circulation cooling and inlet
humidity
adjustment. Because it is distilled quality water, it can also be used for any
use for which
distilled water may be needed in the area of the plant. For example, it can be
used as a
source for drinking water or irrigation water as well. A source for drinking
water or
irrigation water may be particularly useful in desert locations.
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1000671 Accordingly, with the present method and system, integration is
utilized
to increase the gas turbine power output in the LNG plant and to provide a
natural gas
stream suitable for the domestic or local natural gas market. The gain in
energy
efficiency by reducing the temperature of the inlet air entering the gas
turbines can
compensate for the amount of energy required to produce the portion of LNG,
which is
later regasified and can compensate for the refrigerant that is consumed.
1000681 In the integrated methods for operating a liquefied natural gas
plant as
disclosed herein, a single liquefied natural gas plant is utilized to create
natural gas for a
local gas market and liquefied natural gas for transport to a remote market.
The process
comprises cooling and condensing a natural gas stream in a LNG facility
comprising a
refrigeration system to produce LNG. One or more gas turbines are used to
operate
compressors for the refrigeration system of the LNG plant. A portion of the
LNG is
taken to be regasified. A portion of the refrigerant from the refrigeration is
system is
consumed. The temperature of inlet air entering the gas turbines of the
refrigeration
system is reduced by exchanging heat with the portion of the LNG to be
regasified and
with the refrigerant to be consumed, either directly or indirectly. In certain
embodiments, an intermediate heat transfer fluid is used to take refrigeration
from the
portion of the LNG to be regasified and from the consumed refrigerant and the
intermediate heat transfer fluid is used to cool the inlet air. The LNG
produced from the
facility is shipped to remote markets and at least a portion of the regasified
LNG can be
supplied to an outlet pipeline for local gas markets.
1000691 In the presently disclosed methods and system, the improvement
comprises consuming a portion of the refrigerant to cool inlet air to the gas
turbines. In
the integrated LNG method and systems, the improvement further comprises
converting
substantially all of the produced natural gas stream from a well or field to
LNG and then
regasifying a portion. In regasifying a portion of the LNG, the regasification
process is
also used to chill inlet air to gas turbines used in the refrigeration system
of the LNG
plant. This approach enhances the GT power output and efficiency which, in
turn,
increases the LNG production of the plant. The gain in efficiency in LNG
production
can compensate for the additional cost in energy and consumption of the
refrigerant.
1000701 While the invention has been described in detail and with
reference to
specific embodiments thereof, it will be apparent to one skilled in the art
that various
changes and modifications can be made without departing from the spirit and
scope
thereof.
12
