Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHOD FOR PRECOOLING
IN HYDROGEN OR HELIUM LIQUEFACTION PROCESSING
FIELD OF THE DISCLOSURE
[0001] This disclosure relates to a precooling process using liquid nitrogen
in hydrogen or
helium liquefaction. More specifically, the disclosure relates to a method of
precooling
hydrogen or helium gas using a process based on a supply of liquid nitrogen,
incorporating at
least one turboexpander and one or more heat exchangers, together which reduce
the amount
of nitrogen required for precooling and reduce the energy consumed in the
precooling
process.
BACKGROUND OF THE DISCLOSURE
[0002] Liquefaction of hydrogen and helium requires a large expenditure of
energy.
Hydrogen has the second lowest boiling point of all substances, with a boiling
temperature of
-253 C at atmospheric pressure. Only helium has a lower boiling point. The
liquefaction
process is divided into several stages, such as: hydrogen compression, pre-
cooling, and
liquefaction. In the pre-cooling stage of hydrogen liquefaction, the hydrogen
gas may be
cooled from ambient temperature to approximately -191 C. Large scale hydrogen
liquefiers
utilize liquid nitrogen supplied from an associated nitrogen/air liquefaction
plant. Processes
for the liquefaction of hydrogen and helium frequently use liquid nitrogen for
precooling
purposes in the liquefaction process. The use of liquid nitrogen reduces the
overall energy
requirement for production of liquid hydrogen or liquid helium. In turn, the
liquid nitrogen
derived for this employment is produced separately with a substantial
expenditure of energy.
As a means for precooling hydrogen or helium prior to liquefaction, the direct
evaporation of
liquid nitrogen, which is conventionally supplied at low pressure and at a
cold temperature
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for vaporization and superheating, entails large temperature differences
between the
hydrogen or helium warm fluids and the cold nitrogen fluid.
[0003] Figure 5 is an example of the conventional precooling processing of
hydrogen gas
with liquid nitrogen (500). Liquid nitrogen (LIN) is supplied in a stream
(504) and hydrogen
gas (warm or at ambient temperature) is supplied in a stream (501). The liquid
nitrogen
stream (504) and the hydrogen gas stream (501) flow in countercurrent through
a heat
exchanger (502) resulting in a cooled hydrogen gas stream (503) and a warmed
nitrogen gas
stream (505). The condition of supplied liquid nitrogen is typical of that
produced by
cryogenic air separation plants.
[0004] The precooling process directly effects the total energy required for
hydrogen or
helium liquefaction. The energy required for precooling, as represented by the
energy to
produce the required liquid nitrogen, is a substantial part of the total
energy to liquefy liquid
hydrogen or helium. Recent work has concentrated on means to reduce the total
energy
required to liquefy hydrogen or helium by different means for supplying
precooling
refrigeration, and means for reduction of the liquid nitrogen requirement.
SUMMARY OF THE DISCLOSURE
[0005] A method for precooling hydrogen or helium gas prior to liquefaction
using a liquid
nitrogen stream is disclosed. That method includes: a.) providing a
pressurized liquid
nitrogen stream containing liquid nitrogen at a pressure between about 15
bar(a) and about 70
bar(a); b.) passing the pressurized liquid nitrogen stream and a partially-
cooled hydrogen or
helium gas stream through a first heat exchanger that exchanges heat between
the pressurized
liquid nitrogen stream and the partially-cooled hydrogen or helium gas stream
to provide a
first partially-warmed nitrogen stream and a precooled hydrogen or helium gas
stream; c.)
passing the first partially-warmed nitrogen stream through one or more
turboexpanders that
lowers the temperature and pressure of the partially-warmed nitrogen stream to
provide a
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cold nitrogen stream; and d.) passing the cold nitrogen stream through the
first heat
exchanger and through a second heat exchanger to provide the precooled
hydrogen or helium
gas stream, and a fully-warmed nitrogen gas stream. Step (d) may include:
passing the cold
nitrogen stream through the first heat exchanger that exchanges heat between
the cold
nitrogen stream and the partially-cooled hydrogen or helium gas stream to
provide a second
partially-warmed nitrogen gas stream and the precooled hydrogen or helium gas
stream; and
passing the second partially-warmed nitrogen gas stream through the second
heat exchanger
that exchanges heat between the second partially-warmed nitrogen gas stream
and a warm
hydrogen or helium gas stream to provide a fully-warmed nitrogen gas stream
and the
partially-cooled hydrogen or helium gas stream. The first heat exchanger and
the second heat
exchanger may be separate devices, or two parts within a single heat
exchanger. The method
may further include applying an auxiliary refrigeration system coupled to the
second heat
exchanger.
[0006] Step (a) may include: supplying a liquid nitrogen stream produced at a
saturation
pressure of less than about 10 bar(a); followed by increasing the pressure of
the liquid
nitrogen stream to provide the pressurized liquid nitrogen stream. Step (a)
may include:
supplying a liquid nitrogen stream produced at a saturation pressure of less
than about 10
bar(a); splitting the liquid nitrogen stream into a first portion of the
liquid nitrogen stream and
a second portion of the liquid nitrogen stream; and increasing a pressure of
the first portion of
the liquid nitrogen stream to provide the pressurized liquid nitrogen stream.
The second
portion of the liquid nitrogen stream may pass through the first heat
exchanger to provide a
third partially-warmed nitrogen stream. The third partially-warmed nitrogen
stream may pass
through the second heat exchanger to provide a second fully-warmed nitrogen
gas stream.
The pressurized liquid nitrogen has a pressure between about 15 bar(a) and
about 70 bar(a),
or about 20 bar(a) and about 55 bar(a).
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[0007] The pressurized liquid nitrogen stream may be split into a first
pressurized liquid
nitrogen stream and a second pressurized liquid nitrogen stream, and the first
pressurized
liquid nitrogen stream and the second pressurized liquid nitrogen stream
passed separately
through the first heat exchanger to exchange heat between the first and the
second pressurized
liquid nitrogen streams and the partially-cooled hydrogen or helium gas
stream.
[000g] Another method for precooling hydrogen or helium gas using a liquid
nitrogen stream
is disclosed that includes: a.) supplying a liquid nitrogen stream produced at
a saturation
pressure of less than about 10 bar(a); b.) directing a first portion of the
liquid nitrogen stream
to a first heat exchanger to provide a first partially-warmed nitrogen stream;
c.) directing the
first partially-warmed nitrogen stream to a second heat exchanger to provide a
first fully-
warmed nitrogen gas stream; c.) increasing a pressure of a second portion of
the liquid
nitrogen stream to provide a pressurized liquid nitrogen stream at a pressure
between about
15 bar(a) and about 70 bar(a); d.) passing the pressurized liquid nitrogen
stream and a
partially-cooled hydrogen or helium gas stream through the first heat
exchanger in
countercurrent to provide a second partially-warmed nitrogen gas stream and a
precooled
hydrogen or helium gas stream; e.) passing the second partially-warmed
nitrogen gas stream
through the second heat exchanger that exchanges heat between the second
partially-warmed
nitrogen gas stream and a warm hydrogen or helium gas stream to provide a
second fully-
warmed nitrogen gas stream and the partially-cooled hydrogen or helium gas
stream; 11)
passing the second fully-warmed nitrogen gas stream through one or more
turboexpanders
that lower the temperature and pressure of the second fully-warmed nitrogen
gas stream to
provide a cold nitrogen stream; e.) passing the cold nitrogen stream through
the first heat
exchanger that exchanges heat between the cold nitrogen stream and the
partially-cooled
hydrogen or helium gas stream to provide a third partially-warmed nitrogen gas
stream and
the precooled hydrogen or helium gas stream; and E) passing the third
partially-warmed
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nitrogen gas stream through the second heat exchanger that exchanges heat
between the third
partially-warmed nitrogen gas stream and a warm hydrogen or helium gas stream
to provide a
third fully-warmed warm nitrogen gas stream and the partially-cooled hydrogen
or helium
gas stream. Step (g) may include: routing the second fully-warmed nitrogen
stream through
one or more compressors and one or more coolers before passing the second
fully-warmed
nitrogen stream through the one or more turboexpanders. Step (g) may include:
passing the
second fully-warmed nitrogen stream through two turboexpanders connected in
series. The
method may further include applying an auxiliary refrigeration system coupled
to the second
heat exchanger.
[0009] The pressurized liquid nitrogen stream may be split into a first
pressurized liquid
nitrogen stream and a second pressurized liquid nitrogen stream; and the first
pressurized
liquid nitrogen stream and the second pressurized liquid nitrogen stream
routed separately
through the first heat exchanger, and optionally, the second heat exchanger.
[0010] The method may include a system of recooling the second or third fully-
warmed
nitrogen gas stream, the system of recooling comprising: i.) passing the
second or third fully-
warmed nitrogen gas stream through a first compressor and a first cooler to
obtain a
compressed and cooled nitrogen gas stream, wherein the first compressor is
coupled to the
second heat exchanger and to the first cooler; ii.) passing the compressed and
cooled nitrogen
gas stream through one or more turboexpanders; and iii). passing the
turboexpanded nitrogen
gas stream through the second heat exchanger to provide a fourth fully-warmed
nitrogen gas
stream. Step (ii) includes passing the compressed and cooled nitrogen gas
stream through two
turboexpanders connected in series.
[0011] A precooling system using liquid nitrogen for hydrogen or helium
liquefaction is also
disclosed. The system may include: a warm hydrogen or helium gas stream; a
pressurized
liquefied nitrogen stream from a supply of liquefied nitrogen; a heat
exchanger; and at least
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one turboexpander coupled to the heat exchanger and configured to lower a
temperature of a
partially-warmed nitrogen gas stream discharged from the heat exchanger. The
heat
exchanger may be configured to exchange heat between the pressurized liquefied
nitrogen
stream and a warm hydrogen or helium gas stream to increase a temperature of
the
pressurized liquefied nitrogen stream and decrease a temperature of the warm
hydrogen or
helium gas stream to provide a precool ed hydrogen or helium gas stream, and a
warm
nitrogen gas stream,. In another aspect, the system includes a first heat
exchanger configured
to exchange heat between the pressurized liquefied nitrogen stream and a
partially-cooled
hydrogen or helium gas stream to increase a temperature of the pressurized
liquefied nitrogen
stream to provide a partially-warmed nitrogen gas stream, and decrease a
temperature of the
partially-cooled hydrogen or helium gas stream; at least one turboexpander
configured to
lower the temperature of the partially-warmed nitrogen gas stream; and a
second heat
exchanger configured to exchange heat between the partially-warmed nitrogen
gas stream
and the warm hydrogen or helium gas stream to increase a temperature of the
partially-
warmed nitrogen gas stream to provide a fully-warmed nitrogen gas stream, and
to decrease a
temperature of the warm hydrogen or helium gas stream.
[0012] The system may also include at least one compressor and at least one
cooler
configured to receive the warm nitrogen gas stream discharged from the heat
exchanger, at
least one turboexpander configured to receive the warm nitrogen gas stream
after passage
through the at least one compressor and the at least one cooler, and/or
optionally, a valve
coupled to the turboexpander.
BRIEF DESCRIPTION OF THE FIGURES
100131 FIG. 1 is a schematic diagram of a system to precool hydrogen gas using
liquid
nitrogen, a first and second heat exchanger, a turboexpander, and auxiliary
refrigeration.
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[0014] FIG. 2 is a schematic diagram of a system to precool hydrogen gas using
liquid
nitrogen, a first and second heat exchanger, a turboexpander, auxiliary
refrigeration, and
other components.
[0015] FIG. 3 is a schematic diagram of a system to precool hydrogen gas using
liquid
nitrogen, a first and second heat exchanger, multiple turboexpanders, multiple
compressors,
multiple coolers, auxiliary refrigeration, and other components
[0016] FIG. 4 is a schematic diagram of a system to precool hydrogen gas using
liquid
nitrogen, a first and second heat exchanger, two turboexpanders, two
compressors, two
coolers, and other components.
[0017] FIG. 5 is a schematic diagram of a conventional system to precool
hydrogen or
helium gas using liquid nitrogen.
DETAILED DESCRIPTION
[0018] The processes disclosed herein have been developed, in part, to reduce
the amount of
liquid nitrogen required for precooling hydrogen or helium gas in the process
of liquefaction.
These processes and precooling systems employ additional steps and equipment
to more fully
utilize the amount of liquid nitrogen supplied into the precooling system.
That is, the
externally derived liquid nitrogen is consumed at a reduced rate compared to
conventional
precooling systems. It is also understood that where liquid nitrogen has also
been used for
precooling other hydrogen or helium streams employed in the liquefaction
process (the so-
called recycle streams), the means for reducing the liquid nitrogen
consumption therein are
also applicable.
[0019] In a method for precooling hydrogen or helium gas using a liquid
nitrogen stream
disclosed herein, a liquid nitrogen supply is pressurized and supplies most of
its cooling
capacity in heat exchange with the hydrogen or helium gas, which warms the
nitrogen; the
warmed nitrogen is then machine-expanded to a cold temperature and re-
introduced for heat
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exchange with hydrogen or helium. In effect, the supplied liquid nitrogen is
passed through
the same heat exchanger a second time (in a loop), thus reducing the liquid
nitrogen
requirement and the attendant energy required for its own production. The
energy costs to
produce this reduced quantity of liquid nitrogen are thereby reduced. Since
this cost is a
significant component of the energy cost for producing liquid hydrogen or
liquid helium, the
overall cost of liquefaction is reduced, which is of commercial importance.
The costs of
precooling may be reduced by about 20% to about 50%.
[0020] The term "machine-expanded," as used herein, includes any device
utilized to produce
work by reducing the enthalpy of the fluid expanded, such as a turboexpander
or a
reciprocating expansion engine.
[0021] Conventional liquid nitrogen precooling processes for hydrogen have a
liquid nitrogen
expenditure of about 7 to about 10 kg liquid nitrogen per kg liquefied
hydrogen. The
precooling process disclosed herein may have a liquid nitrogen expenditure of
about 4 to
about 6 kg liquid nitrogen per kg liquefied hydrogen, or about 4.30 to about
5.35 kg liquid
nitrogen per kg liquefied hydrogen. This is a significant reduction in liquid
nitrogen
expenditure over the conventional process.
[0022] A method for precooling hydrogen or helium gas using a liquid nitrogen
stream is
disclosed, whereby an overall reduction of the amount of liquid nitrogen is
used compared to
conventional precooling.
[0023] That method includes providing a pressurized liquid nitrogen stream
that may have a
pressure of about 15 bar(a) to about 70 bar(a), about 20 bar(a) to about 60
bar(a), or 20 bar(a)
to about 50 bar(a). The pressurized liquid nitrogen may have a temperature of
about -147 C
to about -196 C, about -169 C to about -195 C, or about -189 C to about -
194 C.
[0024] Pressurized liquid nitrogen may be supplied directly into the method
disclosed herein.
Alternatively liquid nitrogen may be supplied from an external source having a
saturation
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pressure of about 1 bar(a) to about 10 bar(a), which may then be pressurized
by any means
known in the art. The liquid nitrogen may be pressurized by utilizing a pump
or by
compression to increase the pressure.
[0025] In an embodiment, the pressurized liquid nitrogen stream may be split
into a first
pressurized liquid nitrogen stream and a second pressurized liquid nitrogen
stream, and each
of the first pressurized liquid nitrogen stream and the second pressurized
liquid nitrogen
stream may be directed through a first heat exchanger to exchange heat between
each of the
first and second pressurized liquid nitrogen streams and the partially-cooled
hydrogen or
helium gas stream. The two partially-warmed nitrogen streams having passed
separately
through the first heat exchanger may be combined into one stream before being
directed
through at least one turboexpander.
[0026] In an embodiment, a liquid nitrogen stream produced at a saturation
temperature at
less than about 10 bar(a) is supplied into the system and split into a first
portion of the liquid
nitrogen stream and a second (or remaining) portion of the liquid nitrogen
stream. The first
portion of the liquid nitrogen stream may have the pressure increased by any
means known in
the art, e.g., by pump or compression, to provide a pressurized liquid
nitrogen stream, and the
second portion of the liquid nitrogen stream may be directed into the first
heat exchanger, and
then optionally into the second heat exchanger, separately from the routing of
the pressurized
liquid nitrogen stream.
[0027] A "pump" as used herein means a mechanical device to increase the
pressure of a
liquid.
[0028] A warm hydrogen or helium gas stream is supplied for precooling and may
be
supplied from one or more hydrogen or helium feed streams or cycle hydrogen or
helium
feed streams. The warm hydrogen gas stream may be produced from natural gas,
electrolysis
of water, or other chemical methods. A warm hydrogen or helium gas stream may
be
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supplied from a source outside of the liquefaction process or it may be a
recycle stream from
elsewhere in the process. The warm hydrogen gas stream may be at any pressure
suitable for
its eventual liquefaction. The warm hydrogen gas stream may have a pressure
between about
20 bar(a) and about 80 bar(a), or about 20 bar(a) and about 40 bar(a) and/or
have a
temperature of about 25 C to about 35 C. The warm hydrogen gas stream may
have a
composition of about 75% ortho and about 25% para. spin isomers.
[0029] Ortho-para conversion of the hydrogen gas may be incorporated as the
hydrogen gas
is cooled. Ortho-para conversion may occur in the first heat exchanger and in
the second heat
exchanger, with the passages of the heat exchanger(s) optionally packed with a
catalyst for
the feed hydrogen. The catalyst may be any known for use in the art for this
purpose. This
may improve the overall energy efficiency of the liquefaction process. The
precooled
hydrogen gas stream may have a temperature of about -173 C to about -196 C,
about -180 C
to about -196 C, or about -190 C to about -192 C, and/or a pressure of about
15 bar(a) to
about 100 bar(a), or about 20 bar(a) to about 80 bar(a). The precooled
hydrogen gas stream
may be about 53% ortho and about 47% para.
[00301 A "heat exchanger," as used herein, means any device capable of
transferring heat
energy or cold energy from one medium to another medium, such as between at
least two
distinct fluids. Heat exchangers include -direct heat exchangers- and -
indirect heat
exchangers." Thus, a heat exchanger may be of any suitable design, such as a
co-current or
counter-cun-ent heat exchanger, an indirect heat exchanger (e.g. a spiral
wound heat
exchanger or a plate-fin heat exchanger such as a brazed aluminum plate fin
type), direct
contact heat exchanger, shell-and-tube heat exchanger, spiral, hairpin, core,
core-and-kettle,
printed-circuit, double-pipe or any other type of known heat exchanger.
[0031] As used herein a first heat exchanger transfers energy between counter
current
streams in the colder steps of the process, while a second heat exchanger
transfers energy
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between counter current streams in the warmer part of the process. The
precooled hydrogen
or helium gas stream exits from the first heat exchanger, while the fully-
warmed nitrogen gas
stream exits from the second heat exchanger. The first and second heat
exchangers may be
two parts of one heat exchanger, or they may be two separate heat exchangers.
When the first
and second heat exchangers are two parts of one heat exchanger, the heat
exchanger includes
multiple outputs for streams passing therethrough, including, but not limited
to exit points for
valves at different locations on the unit.
[0032] As used herein, the term "indirect heat exchange" means the bringing of
two fluids
into heat exchange relation without any physical contact or intermixing of the
fluids with
each other. Core-in-kettle heat exchangers and brazed aluminum plate-fin heat
exchangers are
examples of equipment that facilitate indirect heat exchange.
[0033] A next step includes passing the partially-warmed nitrogen stream
through at least one
turboexpander that lowers the temperature and pressure of the partially-warmed
nitrogen
stream to provide a cold nitrogen stream. The turboexpander may be coupled to
the first heat
exchanger by any means known in the art. The turboexpander exhaust may flow to
the first
heat exchanger. The turboexpander may include a brake, such as a blower, fan
or an oil pump
that circulates and cools, to dissipate energy. The turboexpander may be
coupled to a
compressor for capturing the energy generated by the turboexpander.
[0034] By passing through one turboexpander, the warm nitrogen stream may be
cooled by
about 30 degrees to about 130 degrees, or about 50 to about 100 degrees,
and/or the pressure
may be reduced by about 2 bar to about 100 bar, 4 bar to about 60 bar, or
about 30 bar to
about 50 bar. By passing the stream through a second turboexpander connected
in series to
the first turboexpander, the temperature and pressure of the stream may be
further reduced.
The first turboexpander may be coupled to the second turboexpander.
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[0035] A "turboexpander" as used herein means any device employed to achieve a
reduction
in temperature by effecting a reduction in pressure, while generating useful
energy which can
be either removed from or captured to assist in the required cooling process
by the
performance of work, such as but not limited to, radial inward flow machines
typically used
in cryogenic processing. The turboexpander uses energy in an expanded gas to
generate
mechanical energy through a rotation. The turboexpander turns at high speed
and then the
energy may be transferred via a shaft to a compressor, which recovers the
energy by
compressing a separate feed gas stream. This process elevates the pressure
feed gas stream to
the compressor, enabling it to supply useful energy back into the system.
[0036] Optionally, the method includes passing the partially-warmed nitrogen
stream through
at least one compressor and at least one turboexpander, in any order, to
provide a cold
nitrogen stream that is routed back through the first heat exchanger or second
heat exchanger.
The method may include passing the partially-warmed nitrogen stream through
two to five
compressors and two to five turboexpanders to provide a cold nitrogen stream
that is routed
back through the first heat exchanger or second heat exchanger. The method may
include
passing the partially-warmed nitrogen stream through two to five compressors,
two to five
turboexpanders, and two to five coolers to provide a cold nitrogen stream that
is routed back
through the first heat exchanger. An equal number of coolers may be used in
the process as
the number of compressors. One or more of the turboexpanders may be connected
by a shaft
to one compressor.
[0037] A "cooler" as used herein means any water or air cooler known in the
art that removes
heat from the system, such as, a fin-fan unit for cooling process streams by
ambient air, a
shell-and-tube unit, or a plate cooler which uses a water or brine system for
cooling process
streams from elevated temperatures to near-ambient temperatures. Passing a
stream through a
cooler may lower the temperature of the stream by about 40 C to about 100 C.
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[0038] When passing the cold nitrogen stream through the first heat exchanger,
this creates a
loop in the process of precooling which is a second passage of the nitrogen
stream though the
first heat exchanger. This allows for the same originally supplied nitrogen to
be recycled and
used in countercurrent for cooling the hydrogen or helium gas stream a second
time in the
first heat exchanger. The cold nitrogen stream may be routed through a valve
before passing
through the first heat exchanger for the second time in the process of
precooling
Turboexpanders have a limited range of pressure ratios (inlet pressure/outlet
pressure), so a
valve may be added to the system to further lower the pressure, for example,
instead of
adding a second turboexpander, if needed. Accordingly, when a valve is used,
there is a
pressure drop in the nitrogen stream across the valve. The valve may decrease
the
temperature and pressure, and increase the % gas in the nitrogen stream.
[0039] After passing through the second heat exchanger, the fully-warmed
nitrogen gas
stream may have a temperature of about 15 C to about 30 C, or about 20 C to
about 28 C,
and a pressure of about 0.5 bar(a) to about 2 bar(a), or about 1 bar(a) to
about 2 bar(a). The
fully-warmed nitrogen gas stream may be routed through another processing loop
comprised
of at least one turboexpander, and optionally at least one compressor, for
pressurizing and
cooling and then reintroduced into the second heat exchanger. The fully-warmed
nitrogen gas
stream may be routed through another processing loop comprised of at least one
turboexpander, and optionally at least one compressor, for pressurizing and
cooling and then
reintroduced into the first heat exchanger and then into second heat
exchanger.
[0040] Also disclosed is a precooling system using liquid nitrogen for
hydrogen or helium
liquefaction. The system may comprise: a warm hydrogen or helium gas stream; a
pressurized liquefied nitrogen stream from a supply of liquefied nitrogen; a
first heat
exchanger configured to exchange heat between the pressurized liquefied
nitrogen stream and
a partially-cooled hydrogen or helium gas stream to increase a temperature of
the pressurized
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liquefied nitrogen stream to provide a partially-warmed nitrogen gas stream,
and decrease a
temperature of the partially-cooled hydrogen or helium gas stream; at least
one turboexpander
configured to lower the temperature of the partially-warmed nitrogen gas
stream; and a
second heat exchanger configured to exchange heat between the partially-warmed
nitrogen
gas stream and the warm hydrogen or helium gas stream to increase a
temperature of the
partially-warmed nitrogen gas stream and decrease a temperature of the warm
hydrogen or
helium gas stream. The first heat exchanger or the second heat exchanger may
be coupled to
one turboexpander. The precooling system may comprise a valve coupled to one
turboexpander. The valve may configured to reduce the pressure of the nitrogen
gas stream.
100411 The precooling system may comprise at least one compressor and at least
one cooler,
and optionally at least one turboexpander, configured to receive the fully-
warmed nitrogen
gas stream after passage through the second heat exchanger. The precooling
system may
comprise at least one turboexpander configured to receive the warm nitrogen
gas stream after
passage through the at least one compressor and the at least one cooler. The
precooling
system may comprise one to four compressors, one to four coolers, and one to
four
turboexpanders configured to receive the fully-warmed nitrogen gas stream
after passage
through the second heat exchanger, with each compressor being coupled to a
cooler, and the
one to four turboexpanders being connected after the compressors and coolers
in the system.
10042] Also disclosed is a precooling system using liquid nitrogen for
hydrogen or helium
liquefaction, the system comprising: a warm hydrogen or helium gas stream; a
pressurized
liquefied nitrogen stream from a supply of liquefied nitrogen; a heat
exchanger configured to
exchange heat between the pressurized liquefied nitrogen stream and a warm
hydrogen or
helium gas stream to increase a temperature of the pressurized liquefied
nitrogen stream to
provide a warm nitrogen gas stream, and decrease a temperature of the warm
hydrogen or
helium gas stream to provide a precooled hydrogen or helium gas stream; and at
least one
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turboexpander coupled to the heat exchanger and configured to lower a
temperature of a
partially-warmed nitrogen gas stream discharged from the heat exchanger. The
precooling
system may also include at least one compressor and at least one cooler
configured to receive
the warm nitrogen gas stream after passage through the heat exchanger, and
optionally, at
least one turboexpander configured to receive the warm nitrogen gas stream
after passage
through the at least one compressor and the at least one cooler. The
precooling system may
also include a valve coupled to the turboexpander configured to reduce the
pressure of the
nitrogen gas stream.
[0043] Described herein are systems and processes relating to precooling
hydrogen or helium
gas using a liquid nitrogen stream. Specific embodiments of the disclosure
include those set
forth in the following paragraphs as described with reference to the Figures.
While some
features are described with particular reference to only one Figure (such as
FIG. 1, 2, 3, 4),
they may be equally applicable to the other Figures and may be used in
combination with the
other Figures or the foregoing discussion.
[0044] Figures 1-4 show non-limiting examples of various systems and processes
100, 200,
300, 400 for precooling hydrogen or helium gas using a liquid nitrogen stream
according to
this disclosure. A liquid nitrogen stream (LIN) 104, 204, 304, 404 is supplied
from any LIN
supply system, such as one or more tankers, tanks, pipelines, or any
combination thereof The
systems include at least one heat exchanger, e.g., a first heat exchanger 131,
231, 331, 431
and a second heat exchanger 130, 230, 330, 430. These systems include a pump
132, 232,
332, 432 to receive the liquid nitrogen stream and increase the pressure to
make a pressurized
liquid nitrogen stream 105, 250, 306, 406. The pressurized liquid nitrogen
stream may be
split into more than one stream, e.g., two streams 250, 240. Warm hydrogen or
helium gas is
supplied from any source in a stream 101, 201, 301, 401 that is routed through
the second
heat exchanger to provide a partially-cooled hydrogen or helium gas stream
102, 202, 302,
CA 03212384 2023- 9- 15
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402, which is routed through the first heat exchanger for further cooling to
provide a
precooled hydrogen or helium gas stream 103, 203, 303, 403.
[0045] FIG. 1 shows a system 100 for precooling hydrogen or helium gas using a
liquid
nitrogen stream. The liquid nitrogen stream 104 is directed through a pump 132
to increase
the pressure. The pressurized liquid nitrogen stream 105 is routed through a
first heat
exchanger 131 in which energy is transferred between the partially-cooled
hydrogen or
helium gas stream 102 and the pressurized liquid nitrogen stream 105, which
flow in
countercurrent, thereby increasing the temperature of the nitrogen stream. The
partially-
warmed nitrogen gas stream 106 is then directed through a turboexpander 133 to
provide a
cold nitrogen gas stream 107 which has a lower pressure and lower temperature
than stream
106. It will be envisioned that the system may include more than one
turboexpander
connected in series for reducing the temperature and pressure of the nitrogen
stream before
re-entry into the first heat exchanger. The disclosure includes alternate
embodiments where,
in each identified location of a turboexpander, multiple turboexpanders may be
connected in
series, such as two, three, or four, where needed to further reduce the
pressure of the stream.
[0046] The cold nitrogen gas stream 107 is then routed through the first heat
exchanger to
complete the loop, and for a second pass of the nitrogen gas stream through
the first heat
exchanger, in which energy is transferred between the partially-cooled
hydrogen or helium
gas stream 102 and the cold nitrogen stream 107, to provide a partially-warmed
nitrogen gas
stream 108 and a precooled hydrogen or helium gas stream 103.
[0047] The partially-warmed nitrogen gas stream 108 is then routed through a
second heat
exchanger 130 in which energy is transferred between the warm hydrogen or
helium gas
stream 101 and the partially-warmed nitrogen gas stream 108, to provide a
fully-warmed
nitrogen gas stream 109 and a partially-cooled hydrogen or helium gas stream
102, which is
then routed through the first heat exchanger 131.
16
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[0048] The second heat exchanger 130 may include auxiliary refrigeration, here
shown as
propene streams 114, 115. Liquid propene stream 114 passes through the second
heat
exchanger which exchanges heat between the auxiliary refrigeration and the
warm hydrogen
or helium gas stream 101, and exits as a gas propene stream 115. The second
heat exchanger
may include auxiliary refrigeration coupled to the second heat exchanger.
Auxiliary
refrigeration supplements coolant in the precooling process and may be
supplied from any
other known sources of refrigeration. Auxiliary refrigeration may be a vapor
compression
refrigeration, absorption refrigeration, mixed refrigerant refrigeration, or
any other means
known to extract heat from the warm hydrogen or helium gas stream. Auxiliary
refrigeration
may comprise of one refrigeration stream, or two refrigeration streams, being
the same or
different. Auxiliary refrigeration may be a propene refrigeration stream which
supplies a
liquid stream at a temperature of about -20 C to -50 C, and exits the system
as a gas stream.
[0049] Having described an embodiment of the disclosure, additional aspects
will now be
described. FIG. 2 illustrates a system 200 for precooling hydrogen or helium
gas using a
liquid nitrogen stream. In FIG. 2, liquid nitrogen is pumped to an elevated
pressure, and, after
vaporizing and superheating for cooling hydrogen, passes through a
turboexpander and
returns to conduct additional cooling of the hydrogen. A valve 235 is shown
between streams
208 and 209 for meeting the aerodynamic limitations of the turboexpander, if
needed.
Auxiliary refrigeration is provided at a temperature level much warmer than
that of liquid
nitrogen as part of the cooling process, for instance, from propene vapor-
compression
refrigeration.
[0050] The system of FIG. 2 is configured so that the split pressurized liquid
nitrogen
streams 240, 250 are routed through the first heat exchanger 231, whereby the
split
pressurized liquid nitrogen streams 240, 250 are warmed and the pressure
remains
substantially constant, e.g., any pressure differential may be less than about
1 bar(a). Each of
17
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the split partially-warmed nitrogen streams 241, 251 exits the first heat
exchanger at a
different output, though it will be envisioned that the streams may exit at
any desired output
to achieve the desired heat exchange. The split partially-warmed nitrogen
streams 241, 251
are then combined to a single partially-warmed nitrogen stream 207, and passed
through a
turboexpander 233 coupled to a brake 234. In passing through the
turboexpander, the single
warm nitrogen stream 207 is cooled, and the pressure decreases, thereby also
increasing the
amount of liquid in the stream, e.g., from about 0% in stream 207 to about 6%
to about 10%
in stream 208. A valve 235 is shown between the turboexpander 233 and first
heat exchanger
231 which decreases the temperature and pressure of the cold nitrogen stream
208 before it is
routed back to, and for a second pass through, the first heat exchanger. With
passage through
the first heat exchanger 231, the cold, low-pressure nitrogen stream 209 is
warmed. In
passing through the first heat exchanger 231, the liquid in cold, low-pressure
nitrogen stream
209 is vaporized such that partially-warmed nitrogen gas stream 210 is about
0% liquid. The
partially-warmed nitrogen gas stream is then directed through the second heat
exchanger 230
wherein the partially-warmed nitrogen gas stream 210 is warmed and a warm
hydrogen or
helium gas stream 201 is cooled to provide a fully-warmed nitrogen gas stream
211 and the
partially-cooled hydrogen or helium gas stream 202. It may be understood that
while it may
appear from the figures that the partially-warmed nitrogen gas stream 210
leaves the first heat
exchanger 231 to then enter the second heat exchanger 230, when the first heat
exchanger and
the second heat exchanger are two parts of a single unit, the stream flows
from the first heat
exchanger directly to the second heat exchanger, while remaining within the
single heat
exchanger unit. The second heat exchanger 230 may include auxiliary
refrigeration, such as
propene streams 214, 215. Liquid propene stream 214 passes through the second
heat
exchanger 230 which exchanges heat between the auxiliary refrigeration and the
warm
hydrogen or helium gas stream 201, such that liquid propene stream 214 passes
through the
18
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second heat exchanger and exits as a gas propene stream 215. Table 2 includes
a listing of the
streams and equipment shown in FIG. 2 and the properties for each of the
streams. The liquid
nitrogen consumption, calculated by dividing the UN supply flow rate by
precooled
hydrogen flow rate (i.e., the flow rate of stream 204/203) is 5.18 kg LIN/kg
LI-12.
UM*
i''''''":glti:64iiii7a7 i'=""''''"rroisv""'""q Iii""romPeigrriOwn
plimmPtifwiqgtliew"Trovitirn."
= ,,-,,:::,::::::.:: :. =
Equipment RATE :!.:'.i N !.. C. .J]]:, bar
(a) ... %
Mali& .:.:.:. il:.:.:. kkE/hr................!!!!i 11
P '''' ..................'' i!!!........ iii liF'
...............E..........5L............,...................
.......0i1..!..P:::::!::::::E
201 625 Hz, 75% o, 25% p 29 38 0
202 625 H2, 75% o, 25% p -42.2 37.8 0
203 625 H2, 52.6% o, -191.1 37.58 0
47.4% p
204 3238 N2 -192.6 1.45 100
250 2207 N2 -189.5 32 100
240 1031 N2 -189.5 32 100
241 2207 N2 -43.6 31.9 0
251 1031 N2 -172.0 31.9 0
207 3238 N2 -118.4 31.9 0
208 3238 N2 -187.2 2.5 7.44
209 3238 N2 -192.6 1.45 4.43
210 3238 N2 -43.6 1.35 0
211 3238 N2 26.9 1.25 0
212 HEAT
EXCHANG
ER
213 HEAT
EXCHANG
ER
214 915.3 PROPENE -43.6 1.25 100
215 915.3 PROPENE -43.61 1.20 0
216 TURBOEXP
ANDER
217 PUMP
234 BRAKE
[0051] FIG. 3 illustrates a process and system 300 for precooling hydrogen or
helium gas
using a liquid nitrogen stream and four turboexpander-compressors and
auxiliary
refrigeration supplied at -26 C and -46 C. The system of FIG. 3 is configured
so that the
liquid nitrogen stream 304 is split and a portion of the liquid nitrogen
supply is routed
19
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through pump 332 to provide a pressurized liquid nitrogen stream 306. The
other portion of
the liquid nitrogen supply 305 is routed through a valve 384 and then stream
325 passes into
the first heat exchanger 331 where it is warmed to provide a first partially-
warmed nitrogen
gas stream 326 which is then passed through the second heat exchanger for
further warming
to provide a first fully-warmed nitrogen gas stream 327. The pressurized
liquid nitrogen
stream 306 also passes through the first heat exchanger 331, whereby the
temperature of the
pressurized liquid nitrogen stream 306 increases and the pressure remains
substantially
constant, e.g., any pressure differential may be less than about 1 bar. The
second partially-
warmed nitrogen gas stream 322 then passes through the second heat exchanger
330 for
further warming, and exiting at a middle output, to provide a nitrogen gas
stream 307, and
passes through turboexpanders 333, 334, each of which is coupled to a
compressor 335, 336,
to provide nitrogen gas streams 308, 309. The turboexpanders may be designed
to drive
compressors, pumps, oil brakes or any other similar power-consuming device to
remove
energy from the system 300. In passing through the first turboexpander 333,
the nitrogen gas
stream 307 is cooled to a cold nitrogen gas stream 308. In passing through the
second
turboexpander 334, the cold nitrogen gas stream 308 is cooled to a cold, low-
pressure
nitrogen gas stream 309. Each turboexpander reduces the pressure of the
nitrogen stream
passing therethrough. There may optionally be a valve (not shown) between the
second
turboexpander and first heat exchanger to decrease the temperature and
pressure of the cold,
low-pressure nitrogen stream before it is routed back to and for a second pass
through the
first heat exchanger. After passage through the first heat exchanger 331, the
third partially-
warmed nitrogen gas stream 310 then passes through the second heat exchanger
330 wherein
the third partially-warmed nitrogen gas stream 310 is warmed and a warm
hydrogen gas
stream 301 is cooled to provide a fully-warmed nitrogen gas stream 311 and the
partially-
cooled hydrogen gas stream 302. The second heat exchanger 330 may include
auxiliary
CA 03212384 2023- 9- 15
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refrigeration, such as two auxiliary refrigeration systems, as shown including
a first auxiliary
refrigeration system including propene streams 350, 351, and a second
auxiliary refrigeration
system including propene streams 360, 361. In these auxiliary refrigeration
systems, liquid
propene streams 350, 360 pass through the second heat exchanger which
exchanges heat
between the propene stream and the warm hydrogen gas stream 301, such that
liquid propene
streams 350, 360 pass through the second heat exchanger and exit as gas
propene streams
351, 361.
[0052] In FIG. 3, the fully-warmed nitrogen gas stream 311 is routed through
four pairs of
compressor 335, 336, 337, 338, followed by cooler 382, 383, 381, 380, and then
routed
through a third and a fourth turboexpander 339, 340. It will be envisioned
that any number of
pairs of compressor and cooler (e.g., between one pair and 6 pairs), followed
by any number
of turboexpanders (e.g., one to four) may be incorporated into the system. The
compressor
followed by the cooler removes the heat of compression by ambient air or
cooling water or
brine. After routing nitrogen stream 311 through the compressor, nitrogen
stream 312 through
the cooler, nitrogen stream 313 through the compressor, nitrogen stream 314
through the
cooler, nitrogen stream 315 through the compressor, nitrogen stream 316
through the cooler,
nitrogen stream 317 through the compressor, nitrogen stream 318 through the
cooler, and
nitrogen streams 319, 320 through the turboexpanders, the nitrogen gas stream
321 passes
through the second heat exchanger 330 and a fully-warmed nitrogen gas stream
323 is
combined with fully-warmed nitrogen gas stream 327 to make a combined fully-
warmed
nitrogen gas stream 324.
[0053] Table 3 includes a listing of the streams and equipment shown in FIG. 3
and the
properties of each of the streams. The liquid nitrogen consumption, calculated
by dividing the
UN supply flow rate by precooled hydrogen flow rate, is 4.30 kg LIN/kg LH2
21
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TAME3
...........Str-66:f&i3F".... TLOWRN rr:'::.. ' .romposnlom.:
=
.]. Egtitipnwnt kg/hr ! ! C bar (a)
............................... '' . . . ..
....................................................
........................,...............................,......_
301 1250 H2, 75% o, 25% p 29 38 0
302 1250 H2, 75% o, 25% p -131.0 37.8 0
303 1250 H2, 52.6% o, -191.1 37.58 0
47.4% p
304 5380 N2 -192.9 1.40 100
305 1280 N2 -192.9 1.40 100
325 1280 N2 -194.3 1.20
98.63
306 4100 N2 -188.5 55.0 100
307 4100 N2 -46.0 54.9 0
308 4100 N2 -117.1 13.0 0
309 4100 N2 -174.4 2.15 0
310 4100 N2 -136.8 2.13 0
311 4100 N2 27.50 2.08 0
312 4100 N2 73.35 3.119 0
313 4100 N2 29.0 3.019 0
314 4100 N2 84.10 4.876 0
315 4100 N2 29.0 4.776 0
316 4100 N2 94.72 8.406 0
317 4100 N2 29.0 8.306 0
318 4100 N2 90.25 14.10 0
319 4100 N2 29.0 14.00 0
320 4100 N2 -36.80 5.00 0
321 4100 N2 -108.1 1.10 0
322 4100 N2 -136.80 54.95 0
323 4100 N2 27.50 1.050 0
324 5380 N2 27.50 1.050 0
326 1280 N2 -136.8 1.150 0
327 1280 N2 27.50 1.100 0
330 HEAT
EXCHANGE
R
331 HEAT
EXCHANGE
R
332 PUMP
333 TURBOEXP
ANDER
334 TURBOEXP
ANDER
335 COMPRESS
OR
336 COMPRESS
OR
22
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TAME3
Stream RA [E
'tOMPOSnTON'
Equipment kg/hr C hal': (a)
N Oltm: .. . . . ..
337 COMPRESS
OR
338 COMPRESS
OR
339 TURBOEXP
ANDER
340 TURBOEXP
ANDER
350 1000 PROPENE -46.00 1.08 100
351 1000 PROPENE -46.42 1.00 0
360 380 PROPENE -26.00 2.433 100
361 380 PROPENE -26.22 2.413 0
[0054] FIG. 4 illustrates a process and system 400 for precooling hydrogen or
helium gas
using a liquid nitrogen stream where the system includes two turboexpander-
compressor
combinations for precooling without an auxiliary refrigeration unit. The
system of FIG. 4 is
configured so that the liquid nitrogen supply is split into two streams, with
a first portion of
the liquid nitrogen supply being routed through pump 432 to provide a
pressurized liquid
nitrogen stream 406. The other portion of the liquid nitrogen supply 405 is
routed through the
first heat exchanger 431 where it is warmed and vaporized to provide a first
partially-warmed
nitrogen gas stream 421, which then passes through the second heat exchanger
for further
warming to provide a first fully-warmed nitrogen gas stream 422. The
pressurized liquid
nitrogen stream 406 is split into two pressurized liquid nitrogen streams 409,
407, each of
which passes through the first heat exchanger 431 and exiting at different
outputs, whereby
the temperature of the pressurized liquid nitrogen streams increases and the
pressure remains
substantially constant, e.g., any pressure differential may be less than about
1 bar(a), and then
combine to a second partially-warmed nitrogen gas stream 411. The second
partially-warmed
nitrogen gas stream 411 then passes through the second heat exchanger 430 for
further
warming to provide a fully-warmed nitrogen gas stream 412. In this example,
fully-warmed
23
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nitrogen gas stream 412 is routed through two pairs of compressor 434. 436,
followed by
cooler 481, 480, and then through turboexpanders 435, 433, each of which is
coupled to one
of the compressors 434, 436. It will be envisioned that any number of pairs of
compressor
and cooler (e.g., between one pair and 6 pairs), followed by any number of
turboexpanders
(e.g., one to four) may be incorporated into the system. After routing stream
412 through a
compressor, stream 413 through a cooler, stream 414 through a compressor,
stream 415
through a cooler, stream 416 through a turboexpander, and stream 417 through a
turboexpander, the cold, low pressure nitrogen gas stream 418 passes through
the first heat
exchanger 431 to provide another partially-warmed nitrogen gas stream 419 and
then through
the second heat exchanger 430 to provide a fully-warmed nitrogen gas stream
420, which is
combined with stream 422 to make a combined fully-warmed nitrogen gas stream
423.
[0055] Table 4 includes a listing of the streams and equipment shown in FIG. 4
and the
properties for each of the streams. The liquid nitrogen consumption,
calculated by dividing
the UN supply flow rate by precooled hydrogen flow rate, is 5.35 kg L1N/kg
LH2.
ViOrrA
::.E10.itifttiq;1
i Equipment kg/lir : .::.: ..... : ., 'C bar
(a)
/0
........
NMANE........A.11..............................................................
; ..............;.........a...................R...........E.....1
1.....t........1:7....;..........N....... ....
,..............A..................; Ul...;..........A..........g
401 1250 H2, 75% o, 25% 29.00 38.00 0
P
402 1250 H2, 75% o, 25% -40.00 37.80 0
P
403 1250 H2, 52.6% o, -191.1 37.58 0
47.4% p
404 6690 N2 -192.9 1.400 100
405 1200 N2 -192.9 1.400 100
406 5490 N2 -191.3 21.00 100
407 4490 N7 -190.7 21.00 0
408 4490 N7 -46.09 20.95 0
409 1000 N7 -190.7 21.00 100
410 1000 N2 -165.0 20.96 100
411 5490 N2 -90,62 20,95 0
412 5490 N2 27.92 20.90 0
413 5490 1\12 106.7 39.31 0
414 54.90 N2 29 39.21 0
24
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TrOr4
ste6afifeecrrtowRATTOMPOSITIOMMTETOrrtr"PRESSURV3*TIQUIM
Equipment õ kg/fir C.' bdr (j.4,)
____________ Number
___________________________________________________________
415 5490 I\T, 113.1 76.61 0
1
416 5490 N2 29.00 76.51 0
417 5490 1\1/ -62.46 17.50 0
418 5490 N2 -160.6 1.20 0
419 5490 N2 -46.09 1.150
420 5490 N2 27.92 1.10 0
421 1200 1\12 -46.09 1.370 0
422 1200 N2 27.92 1.340 0
423 6690 N2 27.91 1.100 0
450 PUMP
451 HEAT
EXCHANGER
452 HEAT
EXCHANGER
453 TURBO
EXPANDER
454 COMPRESSO
R
455 TURBO
EXPANDER
456 COMPRESSO
R
[0056] A conventional precooling process is shown in FIG. 5 and described
above. Table 5
includes a listing of the streams and equipment shown in FIG. 5 and the
properties of each of
the streams. By dividing the flow of liquid nitrogen stream 504 by the flow of
precooled
hydrogen stream 503, the liquid nitrogen requirement is 7.28 kg of liquid
nitrogen per kg of
hydrogen feed (7.28 kg LIN/kg LH2), where the hydrogen also undergoes ortho-
para
conversion.
TABLE 5
giiie4rifZif #15.5Wfati ___________ CeigitOgiftb teMVERADA RCEgglit OVA
. ,., õ .. . õ
õ :, õ
Equipfttet lila ki g g
P
(Number It NM n
CA 03212384 2023- 9- 15
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PCT/US2022/019734
501 625 H2, 75% o, 25% 29.00 38.00 0
503 625 H2, 52.6% o, -191.1 37.58 0
47.4% p
504 4550 N2 -192.9 1.400
99.6
505 4550 N2 27.50 1.200 0
502 HEAT
EXCHANGE
100571 While there have been described what are presently believed to be
various aspects and
certain desirable embodiments of the disclosure, those skilled in the art will
recognize that
changes and modifications may be made thereto without departing from the
spirit of the
disclosure, and it is intended to include all such changes and modifications
as fall within the
true scope of the disclosure.
26
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