U.S. patent application number 12/817664 was filed with the patent office on 2011-12-22 for method and system for periodic cooling, storing, and heating with multiple regenerators.
This patent application is currently assigned to AIR PRODUCTS AND CHEMICALS, INC.. Invention is credited to Fabrice Amy, Paul HIGGINBOTHAM, Robert VERO, Jianguo XU.
Application Number | 20110308276 12/817664 |
Document ID | / |
Family ID | 44352297 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110308276 |
Kind Code |
A1 |
XU; Jianguo ; et
al. |
December 22, 2011 |
METHOD AND SYSTEM FOR PERIODIC COOLING, STORING, AND HEATING WITH
MULTIPLE REGENERATORS
Abstract
Disclosed are a method and system involving pressurizing an
atmospheric gas stream to form at least a compressed atmospheric
gas stream, directing the compressed atmospheric gas stream to a
first regenerator for cooling, pressurizing to above a second
predetermined pressure to form at least a supercritical atmospheric
gas stream, directing the supercritical atmospheric gas stream to a
second regenerator for cooling, reducing pressure to form at least
a liquefied atmospheric gas stream, selectively storing the
liquefied atmospheric gas stream, pressurizing the liquefied
atmospheric gas stream to form at least a pressurized liquefied
atmospheric gas stream, heating the pressurized liquefied
atmospheric gas stream in the second regenerator to form at least a
heated stream, expanding the heated stream to form at least a
medium pressure atmospheric gas stream, directing the medium
pressure atmospheric gas stream to the first regenerator, and
heating the medium pressure atmospheric gas stream in the first
regenerator.
Inventors: |
XU; Jianguo; (Wrightstown,
PA) ; VERO; Robert; (Emmaus, PA) ; Amy;
Fabrice; (Macungie, PA) ; HIGGINBOTHAM; Paul;
(Guildford, GB) |
Assignee: |
AIR PRODUCTS AND CHEMICALS,
INC.
Allentown
PA
|
Family ID: |
44352297 |
Appl. No.: |
12/817664 |
Filed: |
June 17, 2010 |
Current U.S.
Class: |
62/615 |
Current CPC
Class: |
F25J 2230/30 20130101;
F25J 1/0264 20130101; F25J 2205/24 20130101; F25J 2270/06 20130101;
F25J 1/0202 20130101; F25J 1/0015 20130101; F02C 6/16 20130101;
F25J 2230/06 20130101; F25J 2210/06 20130101; F02C 1/04 20130101;
F25J 1/0012 20130101; F25J 2230/42 20130101; F25J 1/0037 20130101;
F25J 1/004 20130101; F25J 1/0042 20130101; Y02E 60/15 20130101;
F25J 2230/40 20130101; Y02E 60/16 20130101; F02C 6/18 20130101;
F25J 1/0251 20130101; F25J 1/0201 20130101 |
Class at
Publication: |
62/615 |
International
Class: |
F25J 1/02 20060101
F25J001/02 |
Claims
1. A regeneration process for periodic cooling, storing, and
heating, the process comprising: pressurizing an atmospheric gas
stream to above a predetermined pressure to form at least a
compressed atmospheric gas stream, the predetermined pressure being
about 2 bara; directing the compressed atmospheric gas stream to a
first regenerator for cooling to form at least a first cooled
stream; directing the first cooled stream from the first
regenerator; pressurizing the first cooled stream to above a second
predetermined pressure to form at least a supercritical atmospheric
gas stream, the second predetermined pressure being about the
critical pressure of the first cooled stream; directing the
supercritical atmospheric gas stream to a second regenerator to
form at least a second cooled stream; directing the second cooled
stream from the second regenerator; reducing the pressure of the
second cooled stream to form at least a liquefied atmospheric gas
stream; selectively storing the liquefied atmospheric gas stream as
a stored liquefied atmospheric gas; pressurizing at least a portion
of the stored liquefied atmospheric gas to above a third
predetermined pressure to form at least a pressurized liquefied
atmospheric gas stream, the third predetermined pressure being
about the critical pressure of the stored liquefied atmospheric
gas; heating the pressurized liquefied atmospheric gas stream in
the second regenerator to form at least a heated stream; directing
the heated stream from the second regenerator; expanding the heated
stream to form at least a medium pressure atmospheric gas stream;
directing the medium pressure atmospheric gas stream to the first
regenerator; and heating the medium pressure atmospheric gas stream
in the first regenerator.
2. The process of claim 1, wherein the pressurizing of the
atmospheric gas stream is performed by a compressor having no
intercoolers.
3. The process of claim 1, wherein the pressurizing of the first
cooled stream is performed by a compressor having no
intercoolers.
4. The process of claim 1, further comprising further cooling the
first cooled stream directed from the first regenerator by an
aftercooler.
5. The process of claim 1, further comprising further heating at
least a portion of the pressurized atmospheric gas by an external
heat source.
6. The process of claim 5, wherein the external heat source is
exhaust gas from a gas turbine.
7. The process of claim 5, wherein the external heat source is a
solar heat collector.
8. The process of claim 1, wherein the atmospheric gas is
substantially air.
9. The process of claim 1, wherein the atmospheric gas is
substantially nitrogen.
10. The process of claim 1, further comprising directing the heated
pressurized atmospheric gas or the heated medium pressure stream to
a gas turbine.
11. The process of claim 1, further comprising expanding the heated
pressurized atmospheric gas or the heated medium pressure stream to
a fourth predetermined pressure to form an expanded atmospheric
gas, the fourth predetermined pressure being about the atmospheric
pressure of the environment.
12. The process of claim 11, further comprising directing the
expanded atmospheric gas to a gas turbine.
13. The process of claim 1, wherein the second cooled stream is
formed in the second regenerator by external cooling provided by a
non-combustible fluid.
14. The process of claim 1, further comprising providing additional
heating or cooling to the system with an indirect regenerator.
15. A system for performing the process of claim 1.
16. A regeneration system for periodic cooling, storing, and
heating, the process comprising: a first compressor for
pressurizing an atmospheric gas stream to above a predetermined
pressure to form at least a compressed atmospheric gas stream, the
predetermined pressure being about 2 bara; a first regenerator
configured for cooling the compressed atmospheric gas stream to
form at least a first cooled stream; a second compressor configured
for pressurizing the first cooled stream to above a second
predetermined pressure to form at least a supercritical atmospheric
gas stream, the second predetermined pressure being about the
critical pressure of the first cooled stream; a second regenerator
configured to cool the supercritical atmospheric gas stream to form
at least a second cooled stream; a pressure reducing device
configured for expanding the second cooled stream to form at least
a liquefied atmospheric gas stream; a storage container configured
for selectively storing the liquefied atmospheric gas stream as a
stored liquefied atmospheric gas; a pump configured for
pressurizing the stored liquefied atmospheric gas to above a third
predetermined pressure to form at least a pressurized liquefied
atmospheric gas stream, the third predetermined pressure being
about the critical pressure of the stored liquefied atmospheric
gas; and an expander configured for expanding a heated stream to
form at least a medium pressure atmospheric gas stream, the heat
stream being formed by heating of the second regenerator; wherein
the second regenerator is configured to heat the pressurized
liquefied atmospheric gas stream to form at least the heated
stream; wherein the first regenerator is configured for heating the
medium pressure atmospheric gas stream.
17. The system of claim 16, further comprising an indirect
regenerator, the indirect regenerator being configured to provide
additional heating or cooling to the system.
18. The system of claim 16, further comprising a gas turbine, the
gas turbine positioned to heat at least a portion of the heated
pressurized atmospheric gas or the medium pressure atmospheric
gas.
19. The system of claim 16, further comprising a solar heat
collector, the solar heat collector positioned to heat at least a
portion of the heated pressurized atmospheric gas or the medium
pressure atmospheric gas.
20. A regeneration process for periodic cooling, storing, and
heating, the process comprising: pressurizing an atmospheric gas
stream to above a predetermined pressure to form at least a
compressed atmospheric gas stream, the predetermined pressure being
about 2 bara; directing the compressed atmospheric gas stream to a
first regenerator for cooling to form at least a first cooled
stream; directing the first cooled stream from the first
regenerator; further cooling the first cooled stream directed from
the first regenerator by an aftercooler to form a further cooled
stream; pressurizing the further cooled stream from the aftercooler
to above a second predetermined pressure to form at least a
supercritical atmospheric gas stream, the second predetermined
pressure being about the critical pressure of the first cooled
stream; directing the supercritical atmospheric gas stream to a
second regenerator to form at least a second cooled stream;
directing the second cooled stream from the second regenerator;
reducing the pressure of the second cooled stream to form at least
a liquefied atmospheric gas stream; selectively storing the
liquefied atmospheric gas stream as a stored liquefied atmospheric
gas; pressurizing at least a portion of the stored liquefied
atmospheric gas to above a third predetermined pressure to form at
least a pressurized liquefied atmospheric gas stream, the third
predetermined pressure being about the critical pressure of the
stored liquefied atmospheric gas; heating the pressurized liquefied
atmospheric gas stream in the second regenerator to form at least a
heated stream; directing the heated stream from the second
regenerator; expanding the heated stream to form at least a medium
pressure atmospheric gas stream; directing the medium pressure
atmospheric gas stream to the first regenerator; heating the medium
pressure atmospheric gas stream in the first regenerator; further
heating at least a portion of the medium pressure atmospheric gas
by an external heat source; expanding the heated medium pressure
atmospheric gas to a fourth predetermined pressure to form an
expanded atmospheric gas, the fourth predetermined pressure being
about the atmospheric pressure of the environment; and directing
the expanded atmospheric gas to a gas turbine.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to a method and system for
periodic cooling, storing, and heating of atmospheric gas. More
specifically, the present invention is directed to a method and
system involving multiple regenerators in a regeneration cycle for
atmospheric gas.
BACKGROUND OF THE INVENTION
[0002] Known systems can cool pressurized air obtained during
off-peak electricity demand hours (off-peak hours) and vaporize the
pressurized air under pressure during peak electricity demand hours
(peak hours).
[0003] Japanese Patent Application, JP4-132837A, which is hereby
incorporated by reference in its entirety, describes a gas turbine
power generation facility comprising a gas turbine for driving a
power generator, a liquefaction facility for liquefying air, a
storage container for storing liquefied fluid, and a vaporization
facility for vaporizing the liquefied fluid and feeding the product
to a gas turbine burner. When the liquefied fluid is pumped from
the storage container, it is vaporized and directed to the gas
turbine burner. This facility suffers from several drawbacks. For
example, liquefaction of air is carried out by using a dedicated
liquefier, which can be inefficient. In addition, the vaporization
of the liquefied fluid and transferring of the refrigeration can be
inefficient based upon including multiple heat transfer steps.
[0004] Japanese Patent Application, JP4-127850, which is hereby
incorporated by reference in its entirety, describes a liquid air
storage electricity generation system that cools, liquefies, and
stores air under normal pressure. The liquid air is warmed and
high-pressure air is extracted as required. The high-pressure air
is used to drive an electricity-generating turbine and generate
electricity. This system suffers from several drawbacks. For
example, although use of refrigeration in liquefied natural gas
vaporization can reduce energy needs for air liquefaction,
liquefied natural gas is not always available. In addition, as a
combustible gas, liquefied natural gas involves safety concerns for
storage and transport, and more importantly, the heat exchanger of
liquefied natural gas, a combustible material, with an oxidizing
gas (for example, air).
[0005] Japanese Patent Application, JP4-191419, which is hereby
incorporated by reference in its entirety, describes methods used
to supply air at a constant specified pressure to a combustion
temperature. In a high-loss method, pressure is increased to a
pressure substantially higher than a specified pressure, and the
pressure is reduced to a constant pressure during use. In a
high-risk method, pressure is raised to a specified level using a
separate water head created by sea water, river water, lake water,
or the like. In the methods of the JP4-191419 patent, air is
liquefied and is reduced in volume as compared with the volume
existing at the atmospheric pressure. The liquid is vaporized and
refrigeration is stored. The stored refrigeration can be used for
the precooling of air aspirated by the air liquefied to reduce the
consumption of motive power by the compressor and to reduce the
rate at which electric power is consumed in the production of
liquid air. This method suffers from the drawback that it does not
provide an efficient process for liquefying air and vaporizing the
stored liquid air.
[0006] Hitachi (Hidefumi Araki, Mitsugu Nakabaru, and Kooichi
Chino, Heat Transfer--Asian Research, 31 (4), 2002), which is
hereby incorporated by reference in its entirety, describes high
pressure air being sent to a combustor of a gas turbine during peak
hours. Such a cycle involves a precooled regenerator. Precooling
may be achieved by vaporization of liquefied natural gas. In some
areas, liquefied natural gas may be unavailable. In addition, as a
combustible gas, liquefied natural gas involves safety concerns for
storage and transport, and more importantly, the heat exchangers of
liquefied natural gas, a combustible material, with an oxidizing
gas (for example, air). Additionally, Hitachi discusses extended
cooling by including a regeneration medium such as pebbles or
concrete. As such, operation of the precooled regenerator, as
disclosed in Hitachi, can result in the regenerator warming up over
cycles due to heat leak, heat introduced by machinery such as
liquid air pumps, and the heat transfer temperature difference
needed for heat transfer to take place in the regenerator and other
heat exchangers if the pressure of the air being cooled is the same
as or similar to that of the air being heated, so such a process is
not sustainable. If the pressure of the air to be heated is much
lower than that of the air being cooled, the process becomes rather
inefficient.
[0007] When there is no external heat, or not enough external heat,
a liquid air storage system with isothermal compression cannot
generate the maximum amount of electricity during peak hours.
Besides, adiabatic compressors are sometimes a less expensive
option for air compression if the energy in the form of higher air
temperature can be efficiently recovered. Since the liquid air
storage system performs best when the air for storage is compressed
to a pressure that is higher than the supercritical pressure of
air, a lot of air compression is involved. Using adiabatic
compressors can reduce the capital cost of the compressor
significantly. However, the power needed for compression is also
increased significantly (the energy input into the air is converted
into the thermal energy contained in the higher temperature of the
air). A method for efficiently recovering the thermal energy of the
compressed air is desirable in order to make the process using
adiabatic compressors cost effective. On the other hand, when the
liquid air storage system is used at a site with no external heat
or not enough external heat, if the air coming out of the
regenerator is not at a very high temperature, the exhaust air from
the air expander can be significantly below ambient temperature if
this exhaust air exits the air expander at close to atmospheric
pressure. That means the expander cannot extract as much energy as
it can when the exhaust air from the air expander is at or close
to, or somewhat higher than ambient temperature. If the
refrigeration in the exhaust air cannot be efficiently used, such a
process is sub-optimal. Keeping the exhaust air from such a high
pressure ratio expander at or above ambient temperature would
require the air to be compressed to a temperature that will make
the air compressor prohibitively expensive if not infeasible with
the prior art processes. An improved system and process are needed
for such situations.
SUMMARY OF THE INVENTION
[0008] One aspect of the present disclosure includes a regeneration
process for periodic cooling, storing, and heating. The process
includes pressurizing an atmospheric gas stream to above a
predetermined pressure to form at least a compressed atmospheric
gas stream (the predetermined pressure being about 2 bara),
directing the compressed atmospheric gas stream to a first
regenerator for cooling to form at least a first cooled stream,
directing the first cooled stream from the first regenerator,
pressurizing the first cooled stream to above a second
predetermined pressure to form at least a supercritical atmospheric
gas stream (the second predetermined pressure being about the
critical pressure of the first cooled stream), directing the
supercritical atmospheric gas stream to a second regenerator to
form at least a second cooled stream, directing the second cooled
stream from the second regenerator, reducing the pressure of the
second cooled stream to form at least a liquefied atmospheric gas
stream, selectively storing the liquefied atmospheric gas stream as
a stored liquefied atmospheric gas, pressurizing at least a portion
of the stored liquefied atmospheric gas to above a third
predetermined pressure to form at least a pressurized liquefied
atmospheric gas stream (the third predetermined pressure being
about the critical pressure of the stored liquefied atmospheric
gas), heating the pressurized liquefied atmospheric gas stream in
the second regenerator to form at least a heated stream, directing
the heated stream from the second regenerator, expanding the heated
stream to form at least a medium pressure atmospheric gas stream,
directing the medium pressure atmospheric gas stream to the first
regenerator, and heating the medium pressure atmospheric gas stream
in the first regenerator.
[0009] Another aspect of the present disclosure includes a
regeneration system. The regeneration system includes a first
compressor for pressurizing an atmospheric gas stream to above a
predetermined pressure to form at least a compressed atmospheric
gas stream (the predetermined pressure being about 2 bara), a first
regenerator configured for cooling the compressed atmospheric gas
stream to form at least a first cooled stream, a second compressor
configured for pressurizing the first cooled stream to above a
second predetermined pressure to form at least a supercritical
atmospheric gas stream (the second predetermined pressure being
about the critical pressure of the first cooled stream), a second
regenerator configured to cool the supercritical atmospheric gas
stream to form at least a second cooled stream, a pressure reducing
device configured for expanding the second cooled stream to form at
least a liquefied atmospheric gas stream, a storage container
configured for selectively storing the liquefied atmospheric gas
stream as a stored liquefied atmospheric gas, a pump configured for
pressurizing the stored liquefied atmospheric gas to above a third
predetermined pressure to form at least a pressurized liquefied
atmospheric gas stream (the third predetermined pressure being
about the critical pressure of the stored liquefied atmospheric
gas), and an expander configured for expanding a heated stream to
form at least a medium pressure atmospheric gas stream (the heat
stream being formed by heating of the second regenerator). The
second regenerator is configured to heat the pressurized liquefied
atmospheric gas stream to form at least the heated stream and the
first regenerator is configured for heating the pressurized
atmospheric gas stream.
[0010] Another aspect of the present disclosure includes a
regeneration process. The process includes pressurizing an
atmospheric gas stream to above a predetermined pressure to form at
least a compressed atmospheric gas stream (the predetermined
pressure being about 2 bara), directing the compressed atmospheric
gas stream to a first regenerator for cooling to form at least a
first cooled stream, directing the first cooled stream from the
first regenerator, further cooling the first cooled stream directed
from the first regenerator by an aftercooler to form a further
cooled stream, pressurizing the first cooled stream after it is
further cooled to above a second predetermined pressure to form at
least a supercritical atmospheric gas stream, the second
predetermined pressure being about the critical pressure of the
first cooled stream, directing the supercritical atmospheric gas
stream to a second regenerator to form at least a second cooled
stream, directing the second cooled stream from the second
regenerator, reducing the pressure of the second cooled stream to
form at least a liquefied atmospheric gas stream, selectively
storing the liquefied atmospheric gas stream as a stored liquefied
atmospheric gas, pressurizing at least a portion of the stored
liquefied atmospheric gas to above a third predetermined pressure
to form at least a pressurized liquefied atmospheric gas stream
(the third predetermined pressure being about the critical pressure
of the stored liquefied atmospheric gas), heating the pressurized
liquefied atmospheric gas stream in the second regenerator to form
at least a heated stream, directing the heated stream from the
second regenerator, expanding the heated stream to form at least a
medium pressure atmospheric gas stream, directing the medium
pressure atmospheric gas stream to the first regenerator, heating
the medium pressure atmospheric gas stream in the first
regenerator, further heating at least a portion of the medium
pressure atmospheric gas by an external heat source, expanding the
heated medium pressure atmospheric gas to a fourth predetermined
pressure to form an expanded atmospheric gas, the fourth
predetermined pressure being about the atmospheric pressure of the
environment, and directing the expanded atmospheric gas to a gas
turbine compressor.
[0011] An advantage of the present disclosure includes greater
efficiency of heating and cooling operations in systems for cooling
and storing atmospheric gas and related systems.
[0012] Another advantage of the present disclosure includes the use
of the liquid air energy storage system regardless of whether there
is an external source of heat.
[0013] Another advantage of the present disclosure includes the use
of the lower cost compressors, specifically, the so-called
"adiabatic compressors," or compressors with no intercoolers for
compression of air or other atmospheric gases.
[0014] Other features and advantages of the present invention will
be apparent from the following more detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows a schematic diagram of a portion of an
exemplary embodiment of a regeneration system having a first
regenerator and a second regenerator according to the
disclosure.
[0016] FIG. 2 shows a schematic diagram of a portion of an
exemplary embodiment of a regeneration system having a first
regenerator, a second regenerator, and an indirect regenerator
according to the disclosure.
[0017] FIG. 3 shows a schematic diagram of a portion of an
exemplary embodiment of a regeneration system having a first
regenerator and a second regenerator according to the
disclosure.
[0018] FIG. 4 shows a schematic diagram of a portion of an
exemplary embodiment of a regeneration system having a first
regenerator and a second regenerator according to the
disclosure.
[0019] FIG. 5 shows a schematic diagram of a portion of an
exemplary embodiment of a regeneration system having a first
regenerator, a second regenerator, and an indirect regenerator
according to the disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Provided is a method and system for cooling and storing an
atmospheric gas during a first operational period of a process
cycle and heating the atmospheric gas during a second operational
period. The system and process involve multiple regenerators in a
regeneration cycle for the atmospheric gas.
[0021] As used herein, the term "atmospheric gas" refers to a gas
that primarily contains nitrogen, argon, oxygen, or combinations
thereof. In one embodiment, the atmospheric gas is a mixture of
nitrogen, argon, and oxygen. In one embodiment, the oxygen content
can be above about 20.95% by volume. In one embodiment, the argon
content can be above about 0.93% by volume. As used herein, the
term "regenerator" refers to a fixed body with flow features and a
heat capacity operated as a periodic heat transfer device providing
cooling when operated in a first operational mode and providing
heating in a second operational mode, or vice versa.
[0022] In general, a stream flows through the flow features (for
example, flow channels) of a regenerator in a first direction
during a first operational period (for example, an off-peak demand
period when the price of electricity is generally lower) and during
the first operational mode (see FIGS. 1, 2, and 3). In the first
operational mode, the regenerator absorbs heat from at least a
portion of the stream directed into the regenerator. This
absorption of heat by the regenerator cools the stream to below a
predetermined temperature to form a stream that is directed from
the regenerator. During a second operational period (for example,
an on-peak demand period when the price of electricity is generally
higher), the same regenerator can be operated in a second
operational mode (see FIGS. 4 and 5). In the second operational
mode, a pressurized liquefied atmospheric gas stream is directed
through the regenerator that provides heat to the pressurized
liquefied atmospheric gas stream. The first operational period and
the second operational period can repeat multiple times as cycles
and the cycles can be repeatedly performed. The first operational
period can be during periods of lower energy demand from the grid
and the second operational period can be during periods of higher
energy demand from the grid.
[0023] A regenerator can be arranged in series with one or more
additional regenerators and/or the regenerator can be arranged in
parallel with one or more additional regenerators. In one
embodiment, the arrangement can reduce longitudinal heat transfer
(longitudinal heat transfer being the heat transfer in the
direction of flow) by connecting multiple regenerator beds in
series. In including a plurality of regenerator beds, it is
desirable that different regenerators are configured for different
values of predetermined parameters (for example, pressure ranges,
temperature ranges, and/or flow ranges). As is defined herein, a
regenerator may have several regenerator beds in series, or in
parallel, or a combination of beds in series and in parallel.
However, if a fluid inlet or outlet, or both a fluid inlet and
outlet, exists in between the generator beds in a regenerator bed
series, these regenerator beds are no longer considered as a single
regenerator, but are considered at least as parts of at least two
regenerators.
[0024] FIG. 1 shows a schematic diagram of a portion of a
regeneration system 101. Specifically, FIG. 1 shows the portion of
the regeneration system 101 used during the first operational
period (for example, an off-peak demand period). In one embodiment
of the regeneration method, an atmospheric gas stream 100 is
pressurized to above a predetermined pressure to form a compressed
atmospheric gas stream 102. The atmospheric gas stream 100 can be
pressurized by a compressor 104 (for example, an adiabatic
compressor or an air compressor). Use of the adiabatic compressor
can pressurize streams to a higher pressure without an intercooler
thereby augmenting benefits of including multiple regenerators (the
benefits can be due to a compressor with intercoolers being more
expensive than an adiabatic compressor and the heat of compression
not being able to be used while the use of the regenerator captures
most of the heat in the compressed air, and due to the fact that
such a system can be used at locations with no external heat
input). In one embodiment where the compressor 104 is an adiabatic
compressor, the compressor 104 can be devoid of intercoolers. In an
alternate embodiment where the compressor 104 is an air compressor,
the atmospheric gas stream 100 (for example, an air stream) is
directed through the air compressor. In this embodiment, impurities
(for example, water vapor, carbon dioxide, and/or other impurities)
are removed by an atmospheric gas purifier (for example, an air
purifier). In one embodiment, the atmospheric gas stream 100 is
pressurized by the compressor 104 to above a predetermined
pressure. The predetermined pressure can be about 2 bara.
[0025] The compressed atmospheric gas stream 102 can form one or
more streams that are directed from the compressor 104. A stream
106 of the one or more streams is directed to a low pressure
regenerator 108 for cooling to form a first cooled stream 110.
[0026] In one embodiment, the low pressure regenerator 108 can be
configured for operation within a predetermined pressure range (for
example, between about 150 psia and about 250 psia, between about
175 psia and about 225 psia, or between about 190 psia and about
210 psia). In another embodiment, the low pressure regenerator 108
can be configured for operation at about a predetermined pressure
(for example, about 200 psia, about 201.6 psia, or about 197.6
psia).
[0027] The first cooled stream 110 is directed from the low
pressure regenerator 108. Additionally or alternatively, the first
cooled stream 110 can be further cooled by cooling water or another
coolant. In one embodiment, the first cooled stream 110 is further
cooled by a water-cooled aftercooler 112 or an ambient-air-cooled
aftercooler.
[0028] The first cooled stream 110 is further pressurized in a
compressor 114. In one embodiment, the compressor 114 includes
intercoolers 116. In another embodiment, the compressor 114 is
devoid of intercoolers 116. The compressor 114 can be configured to
pressurize the first cooled stream 110 to a predetermined pressure.
For example, the compressor 114 can be configured to pressurize the
first cooled stream 110 to the critical pressure of air, the
critical pressure of nitrogen, the critical pressure of the first
cooled stream 110, or any other suitable pressure. Pressurizing the
first cooled stream 110 forms a supercritical atmospheric gas
(forming supercritical atmospheric gas stream 118).
[0029] The supercritical atmospheric gas stream 118 is directed to
a high pressure regenerator 120. In one embodiment, the high
pressure regenerator 120 can be configured for operation within a
predetermined pressure range (for example, between about 800 psia
and about 1300 psia, between about 1225 psia and about 1275 psia,
or between about 1240 psia and about 1260 psia). In another
embodiment, the high pressure regenerator 120 can be configured for
operation at about a predetermined pressure (for example, about
1250 psia, about 1248 psia, or about 1243 psia).
[0030] The second cooled stream 122 is directed from the high
pressure regenerator 120 to an expander 124 (for example, a dense
fluid expander, or an expansion valve). The expander 124 expands
the second cooled stream 122 to a lower pressure to form a
liquefied atmospheric gas stream 126. As used herein, the term
"liquefied" describes at least a substantial portion of the
atmospheric gas stream being in a liquid phase. The liquefied
atmospheric gas stream 126 is then stored in a storage container
128 (for example, a liquid air storage container or a liquid
nitrogen storage container) until it is released during peak hours
(as described below with reference to FIGS. 4 and 5).
[0031] FIG. 2 shows a schematic diagram of a portion of a
regeneration system 201. Specifically, FIG. 2 shows the portion of
the regeneration system 201 used during the first operational
period (for example, an off-peak demand period). Similar to the
embodiment shown in FIG. 1, the atmospheric gas stream 100 (for
example, air) is pressurized by the compressor 104 with no
intercoolers (also known as an adiabatic compressor) to above a
predetermined pressure (for example, 2 bara) to form the compressed
atmospheric gas stream 102. Stream 106 is directed from the
compressor 104 to the low pressure regenerator 108 for cooling to
form the first cooled stream 110.
[0032] The first cooled stream 110 is directed from the low
pressure regenerator 108 and is further cooled by an indirect heat
exchanger 202 with a cooling water stream 204 to form a cooled and
compressed stream 206. The cooled and compressed stream 206 is
directed to a medium pressure compressor 208 to form a pressurized
stream 210. The pressurized stream 210 is directed to an indirect
heat exchanger 212 where it is further cooled by a heat transfer
fluid 214, is directed to a heat exchanger 216 where it is even
further cooled, and then is directed to a high pressure compressor
218.
[0033] The heat transfer fluid 214 can be provided in conjunction
with an indirect regenerator 220. As used herein, the term
"indirect" describes a regenerator that is separate from the flow
of atmospheric gas but provides cooling or heating to the
atmospheric gas or other suitable stream in the system. In one
embodiment, the heat transfer fluid 214 is heated through the
process of cooling the pressurized stream 210. Upon being heated,
the heat transfer fluid 214 is directed to the indirect regenerator
220 that cools the heat transfer fluid 214. The heat transfer fluid
214 is then pumped back to the indirect heat exchanger 216 by a
pump 222 to cool the pressurized stream 210. Such a system allows
the regenerator to work at a lower pressure than the atmospheric
gas being heated and cooled.
[0034] Upon the pressurized stream 210 being cooled and directed to
the high pressure compressor 218, the high pressure compressor 218
further pressurizes the pressurized stream 210 to the critical
pressure to form the supercritical atmospheric gas stream 118.
Similar to the embodiments described above with reference to FIG.
1, the supercritical atmospheric gas stream 118 is directed to the
high pressure regenerator 120 and cooled to a cryogenic level, the
second cooled stream 122 is directed from the high pressure
regenerator 120 to an expander 124 (for example, a dense fluid
expander or an expansion valve), the expander 124 expands the
second cooled stream 122 to a lower pressure to form a liquefied
atmospheric gas stream 126, and the liquefied atmospheric gas
stream 126 is stored in the storage container 128.
[0035] FIG. 3 shows a schematic diagram of a portion of a
regeneration system 301. Specifically, FIG. 3 shows the portion of
the regeneration system 301 used during the first operational
period (for example, an off-peak demand period). Similar to the
embodiment shown in FIGS. 1 and 2, the atmospheric gas stream 100
is pressurized by the compressor 104 (for example, an adiabatic air
compressor) to above a predetermined pressure (for example, 2 bara)
to form the compressed atmospheric gas stream 102 that forms the
stream 106. Stream 106 is directed from the compressor 104 to the
low pressure regenerator 108 for cooling to form the first cooled
stream 110. The first cooled stream 110 is then directed from the
low pressure regenerator 108 and is further cooled by the
water-cooled aftercooler 112 with a cooling water stream 204. The
cooled and compressed stream 206 (which differs from the
embodiments in FIGS. 1 and 2 by being formed by combining a stream
307 from the water-cooled aftercooler 112 and a combined stream 311
described below) is further pressurized in the compressor 114
(which typically includes intercoolers 116), and the compressor 114
is configured to pressurize the first cooled stream 110 to a
predetermined pressure (for example, the critical pressure of the
gas) to form the supercritical atmospheric gas stream 118.
[0036] In addition to some or all of the features shown in FIGS. 1
and 2, FIG. 3 shows regeneration system 301 including a split of
the supercritical atmospheric gas 118 into a first high pressure
stream 302 and a second high pressure stream 304. The first high
pressure stream 302 is directed through an aftercooler 306 for
cooling (see stream 309) and then is split into a first cooled high
pressure stream 308 and a second cooled high pressure stream 310.
The second cooled high pressure stream 310 is directed to a warm
expander 316 where it is expanded to a predetermined pressure (for
example, the pressure of the first cooled stream 110), generates
work, and forms a lower temperature stream 318. The lower
temperature stream 318 is directed to the supplemental heat
exchanger 312 where it is cooled. Within the supplemental heat
exchanger 312, the first cooled high pressure stream 308 is split
into a first stream 320 and a second stream 322. The first stream
320 is cooled to a cryogenic temperature and is directed from the
supplemental heat exchanger 312. The second stream 322 is directed
from the supplemental heat exchanger 312 to a cold expander 324
where the second stream 322 is expanded, generates work, and forms
a cryogenic stream 326. The cryogenic stream 326 is directed into
the supplemental heat exchanger 312, is heated, and is combined
with the lower temperature air stream 318 that is further heated in
the supplemental heat exchanger 312 to form a combined stream 311.
The combined stream 311 is close to about the temperature of the
atmospheric gas stream 100 or about ambient temperature and is
directed to combine with the first cooled stream 110 (after the
first cooled stream 110 is cooled by the water-cooled aftercooler
112) to form the cooled and compressed stream 206.
[0037] Upon being directed from the supplemental heat exchanger
312, the first stream 320 (at the cryogenic temperature) is
combined with the second cooled stream 122 to form a combined
cryogenic stream 330. The combined cryogenic stream 330 is directed
to the expander 124 that expands the combined cryogenic stream 330
to form a lower pressure stream 332 that is directed to a phase
separator 334 that directs the liquefied atmospheric gas stream 126
to the storage container 128 (to be stored until being released
during peak hours) and directs a vapor atmospheric gas stream 336
to the supplemental heat exchanger 312 where the vapor atmospheric
gas stream 336 is heated to about the temperature of the
atmospheric gas stream 100 or about ambient temperature and forms
an exhaust stream 338 that can be vented, used for other processes,
or used within the regeneration system 301, such as for
regeneration of the atmospheric gas cleaner, typically an
adsorption unit (not shown).
[0038] FIG. 4 shows a schematic diagram of a portion of a
regeneration system 401. Specifically, FIG. 4 shows the portion of
the regeneration system 401 used during the second operational
period (for example, an on-peak demand period). The regeneration
system 401 shown in FIG. 4 can be used in conjunction with the
regeneration system 101 shown in FIG. 1 and/or the regeneration
system 301 shown in FIG. 3.
[0039] The regeneration system 401 selectively directs the
liquefied atmospheric gas stream 127 from the storage container 128
during the second operational period. The second operational period
can be initiated based upon any suitable identifiable event. For
example, the second operational period can be based upon patterns
of high electricity usage in a region (for example, time of day,
day of week, etc.), patterns of high electricity usage at a
facility including the regeneration system 401 (for example, while
other processes are being used, while shifts are working, etc.), an
event such as a brown-out or black-out, and/or an individual or
organization initiating a reduction of power consumption (for
example, a power transmission organization requesting a reduction
of power consumption in exchange for a financial incentive).
[0040] The liquefied atmospheric gas stream 127 is directed from
the storage container 128 by pressurizing at least a portion of the
stored liquefied atmospheric gas at a predetermined pressure
thereby forming a pressurized liquefied atmospheric gas stream 402.
For example, the regeneration system 401 can include a pump 404 for
directing the pressurized liquefied atmospheric gas stream 402. The
pump 404 can be configured for high pressure or supercritical
pressure. The pressurized liquefied atmospheric gas stream 402 is
directed to the high pressure regenerator 120. This regenerator is
the same as that in FIG. 1 except that the flow direction of the
fluid going through the regenerator is reversed, and heat is
provided to the fluid from the regenerator instead of the fluid
(the supercritical atmospheric gas stream 118) providing heat to
the regenerator). In the high pressure regenerator 120, at least a
portion of the pressurized liquefied atmospheric gas stream 402 is
heated to a predetermined temperature to form a heated stream 406.
The predetermined temperature can be about the temperature of the
atmospheric gas stream 100 or ambient temperature. In one
embodiment, the heated stream 406 can be further heated in a gas
heat exchanger 412 to form stream 405. Heat in the gas heat
exchanger 412 can be provided by any suitable source. For example,
heat in the gas heat exchanger 412 can be provided by exhaust
stream 414 from a gas turbine (not shown) to form a cooled stream
407. The heated stream 406 is directed from the high pressure
regenerator 120 and toward an expander 408. The expander 408
reduces the heated stream 406 to a predetermined pressure to form a
medium pressure atmospheric gas stream 410. In one embodiment, the
medium pressure atmospheric gas stream 410 can be used to
regenerate an adsorption bed (not shown) at a higher temperature
and/or lower pressure. The adsorption bed can reduce or eliminate
freezing of certain parts of the regeneration system 401 and/or
downstream equipment.
[0041] The medium pressure atmospheric gas stream 410 is directed
to the low pressure regenerator 108 and is heated to form a heated
medium pressure atmospheric gas stream 416. The heated medium
pressure atmospheric gas stream 416 is directed to an expander 418,
expanded, and forms an atmospheric gas exhaust stream 420. The
atmospheric gas exhaust stream 420 can be used for any suitable
purpose. For example, the atmospheric gas exhaust stream 420 can be
used for drying, can be vented into the atmosphere, and/or can be
used in other processes.
[0042] FIG. 5 shows a schematic diagram of a portion of a
regeneration system 501. Specifically, FIG. 5 shows the portion of
the regeneration system 501 used during the second operational
period (for example, an on-peak demand period). The regeneration
system 501 shown in FIG. 5 can be used in conjunction with the
regeneration system 201 shown in FIG. 2.
[0043] Similar to the regeneration system 401 of FIG. 4, the
regeneration system 501 of FIG. 5 selectively directs the liquefied
atmospheric gas stream 127 from the storage container 128 during
the second operational period. The liquefied atmospheric gas stream
127 is directed from the storage container 128 by pressurizing at
least a portion of the stored liquefied atmospheric gas stream 127
at a predetermined pressure thereby forming the pressurized
liquefied atmospheric gas stream 402 (for example, by using a pump
404). The pressurized liquefied atmospheric gas stream 402 is
directed to the high pressure regenerator 120. In the high pressure
regenerator 120, at least a portion of the pressurized liquefied
atmospheric gas stream 402 is heated to a predetermined temperature
to form the heated stream 406.
[0044] In regeneration system 501, the heated stream 406 is
expanded in a high pressure expander 502 to form an expanded stream
504. The expanded stream 504 is directed to an indirect heat
exchanger 506. In regeneration system 501, the indirect heat
exchanger 506 heats the expanded stream 504 to form a further
heated stream 508 that is then directed to the expander 408 (for
example, a medium pressure expander). The indirect heat exchanger
506 heats the expanded stream 504 by transferring heat from the
heat transfer fluid 214 provided in conjunction with the indirect
regenerator 220. The heat transfer fluid 214 is then pumped back to
the indirect regenerator 220 by a pump 222 to re-heat the heat
transfer fluid 214.
[0045] The further heated stream 508 directed to the expander 408
is expanded to a predetermined pressure to form a medium pressure
atmospheric gas stream 410. The medium pressure atmospheric gas
stream 410 is directed to the low pressure regenerator 108 and is
heated to form a heated medium pressure atmospheric gas stream 416.
The heated medium pressure atmospheric gas stream 416 is directed
to an expander 418, expanded, and forms an atmospheric gas exhaust
stream 420. The atmospheric gas exhaust stream 420 can be used for
any suitable purpose. For example, the atmospheric gas exhaust
stream 420 can be used for cooling a data center, can be vented
into the atmosphere, and/or can be used in other processes.
[0046] In an exemplary embodiment, the portion of the regeneration
system 301 shown in FIG. 3 is operated in conjunction with the
portion of the regeneration system 401 shown in FIG. 4. Referring
to FIG. 3, the compressor 104 can be an adiabatic compressor
configured for shaft work of about 43,511 HP with about 81.73%
isentropic efficiency and about 97% mechanical efficiency. The
compressor 114 can be an isothermal compressor configured for shaft
work of about 26,588 HP with about 82% isentropic efficiency and
about 97% mechanical efficiency. The isothermal compressor can
include four stages and can be cooled by the intercoolers 116 to
about 70.degree. F. (21.degree. C.). The warm expander 316 can be
configured for shaft work of about -608 HP with about 85%
isentropic efficiency and 97% mechanical efficiency. The cold
expander 324 can be configured for shaft work of about -409 HP with
about 85% isentropic efficiency and 97% mechanical efficiency. The
expander 124 can be a dense fluid expander configured for shaft
work of about -630 with about 60% isentropic efficiency and 96%
mechanical efficiency. Referring to FIG. 4, the pump 404 for
directing the pressurized liquefied atmospheric gas stream 402 can
be configured for shaft work of about 1,350 HP with about 75%
isentropic efficiency. The expander 408 can be a higher pressure
expander configured for shaft work of about -34,617 HP with 85%
isentropic efficiency and 97% mechanical efficiency. The expander
418 can be a medium pressure expander configured for shaft work of
about -24,525 with about 85% isentropic efficiency and about 97%
mechanical efficiency.
[0047] In this exemplary embodiment (having the regeneration system
301 of FIG. 3 and the regeneration system 401 of FIG. 4), the
exhaust stream 414 directed to the gas heat exchanger 412 shown in
FIG. 4 is directed from a gas turbine (not shown) operated in
conjunction with the compressor 114 shown in FIG. 5 (the isothermal
compressor having four stages cooled by the intercoolers 116). In
this embodiment, the composition of the exhaust stream 414 can be
(in moles) 0.74418 N.sub.2, 0.00896 Ar, 0.13720 O.sub.2, 0.03151
CO.sub.2, and 0.078148 H.sub.2O (vapor). The streams within this
embodiment can have the following temperature (T), pressure (P),
and flow rate (F):
TABLE-US-00001 TABLE 1 Stream # T (.degree. F.) P (psia) F
(lbmol/hr) 100 60 14.69 22,744 102 750 201.6 22,744 110 369 197.6
22,744 118 163 1,248 25,866 122 -307 1,243 21,469 126 -315.5 17
22,744 126 -316 17 21,550 206 67 196.5 25,866 302 163 1,248 4,397
304 163 1,248 21,469 307 70 196.6 25,866 308 70 1,247 3,077 309 70
1,247 4,397 310 70 1,247 1,319 311 41 196.5 1,803 318 -126 198
1,319 320 -281 1,244 1,275 322 -120 1,246 1,803 326 -254 198 1,803
332 -306 30 22,744 336 -315.5 17 1,193.5 338 41.2 14.7 1,193.5 402
-309 1,220 21,550 405 900 1,213 21,550 406 157 2,215 21,550 407 253
12.4 23,393 410 326 100 21,550 414 939 15 23,393 416 745 96 21,550
420 331 14.7 21,550
[0048] The flow conditions, work inputs, and/or work outputs are
based upon the same flow duration of the first operational period
(off-peak operation) and the second operational period (on-peak
operation). In other embodiments, the duration of the first
operational period and the duration of the second operational
period differ. For example, the first operational period (off-peak
operation) can be 10 hours while the second operational period
(on-peak operation) can be 6 hours. In this embodiment, a flow
amount of one or more of the streams and an amount of work by the
expanders during the first operational period can be adjusted. The
adjustment can include reducing the flow amounts of the streams
during the first operational period by multiplying by a factor of
0.6 and reducing the amount of work of the compressor by
multiplying by the same factor.
[0049] In further embodiments, certain components of the
regeneration system can be substituted or removed. For example,
embodiments having only two regenerators can be devoid of a medium
pressure compressor, an expander, an indirect heat exchanger, an
indirect regenerator, and/or a heat transfer fluid cycle including
a pump. Alternatively, in one embodiment, a medium pressure
compressor and expander can be included in the regeneration system
but a regenerator can be substituted for an indirect heat
exchanger. In this embodiment, the regeneration system can be
devoid of a heat transfer fluid cycle including a pump.
[0050] Including adiabatic compressors can also result in benefits
of having multiple regenerators being augmented. In one embodiment,
the amount of available external heat is considered in selecting
the amount of adiabatic compressors and isothermal compressors
included in the regeneration system.
[0051] In one embodiment, one or more expanders within the
regeneration system are coupled to one or more compressors. Such
coupling can eliminate a generator, a motor, and/or losses
associated with the generator and/or the motor.
[0052] In one embodiment having a small plant capacity (for
example, when the expander work is less than about 50 kW), a dense
fluid expander (which has a higher price and higher efficiency) is
replaced with a throttle valve (which has a lower price and lower
efficiency) to reduce capital cost. In a further embodiment, the
capacity of the plant can be analyzed to determine whether a dense
fluid expander or throttle valve is included in the regeneration
system.
[0053] In one embodiment, additional or alternative cooling is
provided to one or more regenerators from a non-combustible source.
In one embodiment where refrigeration is supplemented to the
regeneration system by external refrigeration, the external
refrigeration permits cooling below the critical temperature
thereby extending the operational duration of the regeneration
system. For example, including the external refrigeration can
extend operational sustainability by months or years. Introducing
liquid nitrogen, liquid air, and/or adding a cryogenic refrigerator
into the process can provide such external refrigeration. In one
embodiment, a portion or all of the cooling in the regeneration
system is performed using non-combustible materials. For example,
fluids used in cooling of the refrigeration system are all
non-combustible. As used herein, the term "non-combustible fluid"
typically includes air, argon, nitrogen, oxygen, helium, xenon,
certain fluorinated hydrocarbons, and combinations thereof.
[0054] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *