U.S. patent application number 17/691554 was filed with the patent office on 2022-09-15 for system and method for precooling in hydrogen or helium liquefaction processing.
The applicant listed for this patent is Air Water Gas Solutions, Inc.. Invention is credited to Robert A. Mostello.
Application Number | 20220290919 17/691554 |
Document ID | / |
Family ID | 1000006332821 |
Filed Date | 2022-09-15 |
United States Patent
Application |
20220290919 |
Kind Code |
A1 |
Mostello; Robert A. |
September 15, 2022 |
SYSTEM AND METHOD FOR PRECOOLING IN HYDROGEN OR HELIUM LIQUEFACTION
PROCESSING
Abstract
Described herein are systems and processes for precooling
hydrogen or helium gas streams for liquefaction using liquid
nitrogen having reduced energy consumption and amount of liquid
nitrogen usage. The systems include a stream of pressurized liquid
nitrogen, at least one turboexpander, and at least one heat
exchanger.
Inventors: |
Mostello; Robert A.;
(Bedminster, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Air Water Gas Solutions, Inc. |
Bedminster |
NJ |
US |
|
|
Family ID: |
1000006332821 |
Appl. No.: |
17/691554 |
Filed: |
March 10, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63207684 |
Mar 15, 2021 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25J 1/0221 20130101;
F25J 1/001 20130101; F25J 1/0007 20130101; F25J 1/0072 20130101;
F25J 2270/904 20130101; F25J 2240/12 20130101 |
International
Class: |
F25J 1/02 20060101
F25J001/02; F25J 1/00 20060101 F25J001/00 |
Claims
1. A method for precooling hydrogen or helium gas using a liquid
nitrogen stream, the method comprising: 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 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.
2. The method of claim 1, wherein step (d) comprises: 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.
3. The method of claim 2, wherein the first heat exchanger and the
second heat exchanger are separate devices.
4. The method of claim 1, wherein the first heat exchanger and the
second heat exchanger are parts within a single heat exchanger.
5. The method of claim 1, wherein the pressurized liquid nitrogen
has a pressure between about 15 bar(a) and about 70 bar(a).
6. The method of claim 1, wherein the pressurized liquid nitrogen
has a pressure between about 20 bar(a) and about 55 bar(a).
7. The method of claim 1, wherein step (a) includes the steps of:
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.
8. The method of claim 1, wherein step (a) includes the steps of:
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.
9. The method of claim 8, further comprising passing the second
portion of the liquid nitrogen stream through the first heat
exchanger to provide a third partially-warmed nitrogen stream
10. The method of claim 9, further comprising directing the third
partially-warmed nitrogen stream through the second heat exchanger
to provide a second fully-warmed nitrogen gas stream.
11. The method of claim 1, further comprising applying an auxiliary
refrigeration system coupled to the second heat exchanger.
12. The method of claim 2, wherein the pressurized liquid nitrogen
stream is split into a first pressurized liquid nitrogen stream and
a second pressurized liquid nitrogen stream, and wherein the first
pressurized liquid nitrogen stream and the second pressurized
liquid nitrogen stream are 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.
13. The method of claim 1, wherein step (c) includes passing the
first partially-warmed nitrogen stream through one or two
turboexpanders.
14. The method of claim 1, wherein step (c) includes passing the
first partially-warmed nitrogen stream through one or more
compressors before passing through the one or more
turboexpanders.
15. The method of claim 2, further comprising applying an auxiliary
refrigeration system coupled to the second heat exchanger.
16. A method for precooling hydrogen or helium gas using a liquid
nitrogen stream, the method comprising: 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; d. 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); e. 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; f. 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; g. 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; h. 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 i. passing the third
partially-warmed 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.
17. The method of claim 16, wherein step (g) comprises: 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.
18. The method of claim 16, wherein step (g) includes passing the
second fully-warmed nitrogen stream through two turboexpanders
connected in series.
19. The method of claim 16, wherein the pressurized liquid nitrogen
stream is split into a first pressurized liquid nitrogen stream and
a second pressurized liquid nitrogen stream; and wherein the first
pressurized liquid nitrogen stream and the second pressurized
liquid nitrogen stream are routed separately through the first heat
exchanger.
20. The method of claim 16, wherein the first heat exchanger and
the second heat exchanger are separate devices.
21. The method of claim 16, wherein the first heat exchanger and
the second heat exchanger are parts within a single heat
exchanger.
22. The method of claim 16, further comprising applying an
auxiliary refrigeration system coupled to the second heat
exchanger.
23. The method of claim 16, further including 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; and 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.
24. The method of claim 23, wherein step (ii) includes passing the
compressed and cooled nitrogen gas stream through two
turboexpanders connected in series.
25. 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 nitrogen gas
stream; and at least 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.
26. The precooling system of claim 25, further comprising at least
one compressor and at least one cooler configured to receive the
warm nitrogen gas stream discharged from the heat exchanger.
27. The precooling system of claim 26, further comprising 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.
28. The precooling system of claim 26, further comprises a valve
coupled to the turboexpander configured to reduce the pressure of
the nitrogen gas stream.
29. A precooling system using liquid nitrogen for hydrogen or
helium liquefaction, the system comprising: a warm hydrogen gas
stream 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 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.
30. The precooling system of claim 29, further comprising at least
one compressor and at least one cooler configured to receive the
fully-warmed nitrogen gas stream after passage through the second
heat exchanger.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority benefit under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Application No. 63/207,684, filed
Mar. 15, 2021, the contents of which is incorporated by reference
herein in its entirety.
FIELD OF THE DISCLOSURE
[0002] 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
[0003] 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.degree. 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.degree. 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 for vaporization and superheating,
entails large temperature differences between the hydrogen or
helium warm fluids and the cold nitrogen fluid.
[0004] FIG. 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.
[0005] 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
[0006] 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 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.
[0007] 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).
[0008] 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.
[0009] 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; f.) 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 f) passing the third
partially-warmed 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.
[0010] 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.
[0011] 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.
[0012] 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 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 precooled
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.
[0013] 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
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] FIG. 5 is a schematic diagram of a conventional system to
precool hydrogen or helium gas using liquid nitrogen.
DETAILED DESCRIPTION
[0019] 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.
[0020] 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 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%.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.degree. C. to about -196.degree. C., about
-169.degree. C. to about -195.degree. C., or about -189.degree. C.
to about -194.degree. C.
[0025] 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 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.
[0026] 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.
[0027] 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.
[0028] A "pump" as used herein means a mechanical device to
increase the pressure of a liquid.
[0029] 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 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.degree. C. to about 35.degree. C. The warm
hydrogen gas stream may have a composition of about 75% ortho and
about 25% para spin isomers.
[0030] 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.degree. C. to about -196.degree. C., about -180.degree. C. to
about -196.degree. C., or about -190.degree. C. to about
-192.degree. 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.
[0031] 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-current 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.
[0032] 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 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.degree. C. to about
100.degree. C.
[0039] 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.
[0040] After passing through the second heat exchanger, the
fully-warmed nitrogen gas stream may have a temperature of about
15.degree. C. to about 30.degree. C., or about 20.degree. C. to
about 28.degree. 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.
[0041] 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 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.
[0042] 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.
[0043] 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 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.
[0044] 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.
[0045] FIGS. 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, 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.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.degree. C. to -50.degree. C., and exits
the system as a gas stream.
[0050] 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.
[0051] 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 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 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 LIN supply flow rate by precooled hydrogen flow rate
(i.e., the flow rate of stream 204/203) is 5.18 kg LIN/kg
LH.sub.2.
TABLE-US-00001 TABLE 2 FLOW Stream or RATE TEMP. PRESSURE LIQUID
Equipment Number kg/hr COMPOSITION .degree. C. bar (a) % 201 625
H.sub.2, 75% o, 25% p 29 38 0 202 625 H.sub.2, 75% o, 25% p -42.2
37.8 0 203 625 H.sub.2, 52.6% o, -191.1 37.58 0 47.4% p 204 3238
N.sub.2 -192.6 1.45 100 250 2207 N.sub.2 -189.5 32 100 240 1031
N.sub.2 -189.5 32 100 241 2207 N.sub.2 -43.6 31.9 0 251 1031
N.sub.2 -172.0 31.9 0 207 3238 N.sub.2 -118.4 31.9 0 208 3238
N.sub.2 -187.2 2.5 7.44 209 3238 N.sub.2 -192.6 1.45 4.43 210 3238
N.sub.2 -43.6 1.35 0 211 3238 N.sub.2 26.9 1.25 0 212 HEAT
EXCHANGER 213 HEAT EXCHANGER 214 915.3 PROPENE -43.6 1.25 100 215
915.3 PROPENE -43.61 1.20 0 216 TURBOEXPANDER 217 PUMP 234
BRAKE
[0052] 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.degree. C. and -46.degree. 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 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
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.
[0053] 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.
[0054] 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 LIN supply
flow rate by precooled hydrogen flow rate, is 4.30 kg LIN/kg
LH.sub.2
TABLE-US-00002 TABLE 3 Stream or FLOW RATE TEMP. PRESSURE LIQUID
Equipment Number kg/hr COMPOSITION .degree. C. bar (a) % 301 1250
H.sub.2, 75% o, 25% p 29 38 0 302 1250 H.sub.2, 75% o, 25% p -131.0
37.8 0 303 1250 H.sub.2, 52.6% o, -191.1 37.58 0 47.4% p 304 5380
N.sub.2 -192.9 1.40 100 305 1280 N.sub.2 -192.9 1.40 100 325 1280
N.sub.2 -194.3 1.20 98.63 306 4100 N.sub.2 -188.5 55.0 100 307 4100
N.sub.2 -46.0 54.9 0 308 4100 N.sub.2 -117.1 13.0 0 309 4100
N.sub.2 -174.4 2.15 0 310 4100 N.sub.2 -136.8 2.13 0 311 4100
N.sub.2 27.50 2.08 0 312 4100 N.sub.2 73.35 3.119 0 313 4100
N.sub.2 29.0 3.019 0 314 4100 N.sub.2 84.10 4.876 0 315 4100
N.sub.2 29.0 4.776 0 316 4100 N.sub.2 94.72 8.406 0 317 4100
N.sub.2 29.0 8.306 0 318 4100 N.sub.2 90.25 14.10 0 319 4100
N.sub.2 29.0 14.00 0 320 4100 N.sub.2 -36.80 5.00 0 321 4100
N.sub.2 -108.1 1.10 0 322 4100 N.sub.2 -136.80 54.95 0 323 4100
N.sub.2 27.50 1.050 0 324 5380 N.sub.2 27.50 1.050 0 326 1280
N.sub.2 -136.8 1.150 0 327 1280 N.sub.2 27.50 1.100 0 330 HEAT
EXCHANGER 331 HEAT EXCHANGER 332 PUMP 333 TURBOEXPANDER 334
TURBOEXPANDER 335 COMPRESS OR 336 COMPRESS OR 337 COMPRESS OR 338
COMPRESS OR 339 TURBOEXPANDER 340 TURBOEXPANDER 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
[0055] 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
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.
[0056] 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 LIN supply
flow rate by precooled hydrogen flow rate, is 5.35 kg LIN/kg
LH.sub.2.
TABLE-US-00003 TABLE 4 Stream or FLOW RATE TEMP. PRESSURE LIQUID
Equipment Number kg/hr COMPOSITION .degree. C. bar (a) % 401 1250
H.sub.2, 75% o, 25% 29.00 38.00 0 P 402 1250 H.sub.2, 75% o, 25%
-40.00 37.80 0 P 403 1250 H.sub.2, 52.6% o, -191.1 37.58 0 47.4% p
404 6690 N.sub.2 -192.9 1.400 100 405 1200 N.sub.2 -192.9 1.400 100
406 5490 N.sub.2 -191.3 21.00 100 407 4490 N.sub.2 -190.7 21.00 0
408 4490 N.sub.2 -46.09 20.95 0 409 1000 N.sub.2 -190.7 21.00 100
410 1000 N.sub.2 -165.0 20.96 100 411 5490 N.sub.2 -90.62 20.95 0
412 5490 N.sub.2 27.92 20.90 0 413 5490 N.sub.2 106.7 39.31 0 414
54.90 N.sub.2 29 39.21 0 415 5490 N.sub.2 113.1 76.61 0 416 5490
N.sub.2 29.00 76.51 0 417 5490 N.sub.2 -62.46 17.50 0 418 5490
N.sub.2 -160.6 1.20 0 419 5490 N.sub.2 -46.09 1.150 420 5490
N.sub.2 27.92 1.10 0 421 1200 N.sub.2 -46.09 1.370 0 422 1200
N.sub.2 27.92 1.340 0 423 6690 N.sub.2 27.91 1.100 0 450 PUMP 451
HEAT EXCHANGER 452 HEAT EXCHANGER 453 TURBO EXPANDER 454 COMPRESSOR
455 TURBO EXPANDER 456 COMPRESSOR
[0057] 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 LH.sub.2), where the hydrogen also undergoes
ortho-para conversion.
TABLE-US-00004 TABLE 5 Stream or Equipment FLOW RATE TEMPERATURE
PRESSURE LIQUID Number kg/hr COMPOSITION .degree. C. bar (a) % 501
625 H.sub.2, 75% o, 25% 29.00 38.00 0 P 503 625 H.sub.2, 52.6% o,
-191.1 37.58 0 47.4% p 504 4550 N.sub.2 -192.9 1.400 99.6 505 4550
N.sub.2 27.50 1.200 0 502 HEAT EXCHANGER
[0058] 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.
* * * * *