U.S. patent application number 12/608087 was filed with the patent office on 2011-05-05 for reinforced thermal energy storage pressure vessel for an adiabatic compressed air energy storage system.
Invention is credited to Clarissa S.K. Belloni, Cristina Botero, Matthias Finkenrath, Sebastian W. Freund, Miguel Angel Gonzalez Salazar, Stephanie Marie-Noelle Hoffmann.
Application Number | 20110100583 12/608087 |
Document ID | / |
Family ID | 42983449 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110100583 |
Kind Code |
A1 |
Freund; Sebastian W. ; et
al. |
May 5, 2011 |
REINFORCED THERMAL ENERGY STORAGE PRESSURE VESSEL FOR AN ADIABATIC
COMPRESSED AIR ENERGY STORAGE SYSTEM
Abstract
A thermal energy storage system comprises a pressure vessel
configured to withstand a first pressure, wherein the pressure
vessel has a wall comprising an outer surface and an inner surface
surrounding an interior volume of the pressure vessel. The interior
volume of the pressure vessel has a first end in fluid
communication with one or more compressors and one or more
turbines, and a second end in fluid communication with at least one
compressed air storage component. A thermal storage medium is
positioned in the interior volume, and at least one reinforcement
structure is affixed to the outer surface of the wall, wherein the
at least one reinforcement structure configured to reinforce the
wall to withstand a second pressure greater than the first
pressure.
Inventors: |
Freund; Sebastian W.;
(Unterfohring, DE) ; Finkenrath; Matthias;
(Garching b. Muenchen, DE) ; Botero; Cristina;
(Cambridge, MA) ; Belloni; Clarissa S.K.; (Oxford,
GB) ; Gonzalez Salazar; Miguel Angel; (Munchen,
DE) ; Hoffmann; Stephanie Marie-Noelle; (Muenchen,
DE) |
Family ID: |
42983449 |
Appl. No.: |
12/608087 |
Filed: |
October 29, 2009 |
Current U.S.
Class: |
165/10 ;
29/890.03; 29/890.034; 29/897.34 |
Current CPC
Class: |
Y02E 60/16 20130101;
F17C 2223/0123 20130101; Y02E 60/15 20130101; F17C 2201/0104
20130101; Y10T 29/49357 20150115; F17C 2203/012 20130101; Y10T
29/4935 20150115; F28D 17/02 20130101; F02C 7/10 20130101; F17C
2270/0155 20130101; Y10T 29/49632 20150115; F17C 2227/0157
20130101; F17C 2223/035 20130101; F17C 2203/0678 20130101; F17C
2221/031 20130101; F02C 1/005 20130101; F02C 6/16 20130101 |
Class at
Publication: |
165/10 ;
29/890.03; 29/890.034; 29/897.34 |
International
Class: |
F28D 17/02 20060101
F28D017/02; B21D 53/02 20060101 B21D053/02 |
Claims
1. A thermal energy storage system comprising: a pressure vessel
configured to withstand a first pressure, the pressure vessel
having a wall comprising: an outer surface; and an inner surface
surrounding an interior volume of the pressure vessel, the interior
volume having: a first end in fluid communication with one or more
compressors and one or more turbines; and a second end in fluid
communication with at least one compressed air storage component; a
thermal storage medium positioned in the interior volume; and at
least one reinforcement structure affixed to the outer surface of
the wall; the at least one reinforcement structure configured to
reinforce the wall to withstand a second pressure greater than the
first pressure.
2. The thermal energy storage system of claim 1 wherein the at
least one reinforcement structure comprises a plurality of steel
rods interconnected to form a trussed framework about the outer
surface of the wall.
3. The thermal energy storage system of claim 2 further comprising
a steel rim disposed about an outer circumference of the trussed
framework.
4. The thermal energy storage system of claim 1 wherein the at
least one reinforcement structure extends into the interior volume
of the pressure vessel.
5. The thermal energy storage system of claim 4 wherein the at
least one reinforcement structure comprises a plurality of steel
rods forming a spoke-shaped framework within the interior volume of
the pressure vessel.
6. The thermal energy storage system of claim 1 wherein the at
least one reinforcement structure comprises: a plurality of first
rods interconnected between a plurality of wall-mounted anchors and
a circumferential rim to form a trussed framework about the outer
surface of the wall; and a plurality of second rods forming a
spoke-shaped framework within the interior volume of the pressure
vessel.
7. The thermal energy storage system of claim 1 wherein the at
least one reinforcement structure comprises a plurality of
reinforcement structures disposed along a length of the pressure
vessel.
8. The thermal energy storage system of claim 1 wherein the wall of
the pressure vessel is formed of concrete.
9. The thermal energy storage system of claim 1 wherein the thermal
storage medium is a porous thermal storage medium disposed within
the interior volume of the pressure vessel.
10. The thermal energy storage system of claim 9 wherein the porous
thermal storage medium comprises at least one of natural stone,
ceramic, concrete, cast iron, nitrate salt, and mineral oil.
11. The thermal energy storage system of claim 1 wherein the
pressure vessel is cylindrical in shape.
12. A method of forming a thermal energy storage pressure vessel,
the method comprising: forming a wall having a predetermined height
and thickness, wherein an inner surface of the wall bounds an
interior volume therein; affixing a reinforcement structure to a
surface of the wall at a first location; affixing at least one
additional reinforcement structure to a surface of the wall at
another location along the height of the wall; and disposing a
porous thermal storage medium within the interior volume.
13. The method of claim 12 wherein the affixing of a reinforcement
structure to the surface of the wall comprises: affixing a
plurality of anchors to an outside surface of the wall; attaching a
plurality of rods to the anchors at a first end of the rods; and
attaching the plurality of rods to a rim at a second end of the
rods such that the plurality of anchors, the plurality of rods, and
the rim form a trussed framework about an outside surface of the
wall.
14. The method of claim 12 wherein affixing the reinforcement
structure to the surface of the wall comprises: affixing a
plurality of anchors to an outside surface of the wall; and
affixing a plurality of rods to the plurality of anchors, the
plurality of rods passing through the wall to form a spoke-shaped
framework within the interior volume of the wall.
15. The method of claim 12 wherein affixing the reinforcement
structure to the surface of the wall comprises: affixing a
plurality of anchors to an outside surface of the wall; attaching a
plurality of first rods to the anchors at a first end of the first
rods; attaching the plurality of first rods to a rim at a second
end of the first rods such that the plurality of anchors, plurality
of first rods, and the rim form a trussed framework about an
outside surface of the wall; and affixing a plurality of second
rods to the plurality of anchors, the plurality of second rods
passing through the wall to form a spoke-shaped framework within
the interior volume of the wall.
16. A thermal energy storage pressure vessel comprising: a concrete
cylindrical wall bounding an interior volume, wherein the interior
volume is configured to allow air passage therethrough; at least
one reinforcing structure affixed to an outer surface of the
concrete cylindrical wall; and a porous thermal matrix material
disposed within the interior volume of the concrete cylindrical
wall, wherein the porous thermal matrix material is configured to
allow air passage therethrough.
17. The thermal energy storage pressure vessel of claim 16 wherein
the at least one reinforcing structure comprises a steel ring and a
plurality of trusses interconnected to form a framework about the
outer surface of the concrete cylindrical wall.
18. The thermal energy storage pressure vessel of claim 16 wherein
the at least one reinforcing structure extends into the inner
volume of the concrete cylindrical wall.
19. The thermal energy storage pressure vessel of claim 18 wherein
the at least one reinforcing structure comprises a plurality of
interconnected steel rods affixed at a common centerpoint within
the inner volume of the concrete cylindrical wall.
20. The thermal energy storage pressure vessel of claim 16 wherein
the at least one reinforcing structure is secured to the outer
surface of the concrete cylindrical wall by a plurality of anchors.
Description
BACKGROUND OF THE INVENTION
[0001] Embodiments of the invention relate generally to compressed
air energy storage (CAES) systems and, more particularly, to
thermal energy storage (TES) pressure vessels in an adiabatic CAES
system.
[0002] CAES systems allow the generation of electricity without
producing substantial emissions and/or consuming vast quantities of
natural resources. CAES systems typically include a compression
train having one or more compressors. The one or more compressors
compress intake air in a compression stage for storage in a cavern,
porous rock formation, depleted natural gas/oil field, or other
compressed air storage component. The compressed air is then later
used to drive turbines to produce electrical energy in an energy
generation stage, which can in turn be provided to the utility
grid. Often, if utility energy is used to power the compression
train during the compression stage, the compression train operates
during the off-peak hours of utility plants. The energy generation
stage of the CAES in turn typically operates during high energy
demand times. Alternatively, energy from renewable sources, such as
energy from wind mills or solar panel arrays, may be used to power
the compression train during the compression stage to compress and
deliver air to the compressed air storage location (e.g., a
cavern). In this way, the compression train may be operated during
times other than off-peak hours, and existing utility energy may be
preserved.
[0003] One type of CAES system is known as a diabatic-CAES system.
In a diabatic-CAES system, heat generated by the compression train
is typically lost to the ambient environment. That is, the heat of
compression may be largely present when entering the cavern or
other compressed air storage component, but its energetic value and
availability is diminished as the compressed air mixes with the
cavern air and further cools to ambient temperature during storage.
Thus, when the compressed air stored in the cavern or compressed
air storage component is to be used to drive one or more turbines
to produce electrical energy, the compressed air is typically
reheated prior to entering the turbines. This reheating step is
typically performed using a natural gas-fired recuperator
positioned between the compressed air storage component and the one
or more turbines. Due to this reheating step, the overall
efficiency of the diabatic-CAES system is reduced, and the use of
natural gas to fuel the recuperator leads to carbon emissions and
natural resource consumption.
[0004] Adiabatic-CAES, or ACAES, systems are capable of improving
system efficiency by capturing and storing the heat of compression
for later use. In such a system, one or more thermal energy storage
(TES) units are positioned between the compressor and the cavern.
Typically, a TES unit contains therein a medium for heat storage,
such as concrete, stone, a fluid (e.g., oil), a molten salt, or a
phase-change material. Hot air from the compression stage is passed
through the TES unit, thereby transferring its heat of compression
to the medium in the process. Thus, unlike diabatic-CAES systems,
ACAES systems do not lose all of the heat generated by the
compression train, but instead store some of the heat within the
TES unit or units. The compressed air then enters the cavern at or
near ambient temperature.
[0005] When the compressed air stored within the cavern or other
compressed air storage unit is to be withdrawn to drive the one or
more turbines to produce electrical energy, the compressed air
passes back through the TES unit, thereby reheating the compressed
air prior to entry into the turbine or turbines. In this way, ACAES
systems do not necessitate additional natural gas-fired
recuperation to reheat the compressed air exiting the cavern or
other compressed air storage component. Thus, ACAES systems provide
improved efficiency over diabatic-CAES systems, with fewer (if any)
carbon emissions and little to no natural resource consumption.
[0006] TES units built to effectively store heat generated during
the compression cycle of the compression train are constructed to
withstand the high heat fluctuations and high pressure associated
with ACAES systems. For example, the compressed air temperature
exiting the compression train may vary from 250.degree. C. to
750.degree. C., while the temperature of the compressed air
entering the TES unit from the cavern is at or near ambient
temperature. Likewise, the TES units are designed to withstand
pressures of 65-85 bar. To withstand such high temperatures and
pressures, current proposals for TES units involve the construction
of large concrete cylinders filled with a medium for heat storage.
Due to their large diameter, these TES units are formed having
thick, pre-stressed and steel-reinforced concrete walls, which
enable the TES unit to withstand the high tension forces in the
wall created by the pressure therein. However, construction of such
thick concrete walls leads to substantial engineering difficulties
and high costs, thereby reducing the feasibility of implementing an
ACAES system as opposed to a less efficient diabatic-CAES system.
Furthermore, high operating temperatures and temperature cycles
induce damaging thermal stresses into the concrete walls, and these
stresses are amplified as the concrete walls grow thicker.
[0007] Therefore, it would be desirable to design an apparatus and
method that overcomes the aforementioned drawbacks related to TES
unit construction.
BRIEF DESCRIPTION OF THE INVENTION
[0008] Aspects of the invention provide a system and method for a
TES unit having at least one reinforced structure affixed thereto
to allow the TES unit to withstand both high pressures and high
temperatures. The at least one reinforced structure enables the
wall of the TES unit to have a minimal thickness.
[0009] In accordance with one aspect of the invention, a thermal
energy storage system is disclosed, the thermal energy storage
system comprising a pressure vessel configured to withstand a first
pressure, wherein the pressure vessel has a wall comprising an
outer surface and an inner surface surrounding an interior volume
of the pressure vessel. The interior volume of the pressure vessel
has a first end in fluid communication with one or more compressors
and one or more turbines, and a second end in fluid communication
with at least one compressed air storage component. A thermal
storage medium is positioned in the interior volume, and at least
one reinforcement structure is affixed to the outer surface of the
wall, wherein the at least one reinforcement structure configured
to reinforce the wall to withstand a second pressure greater than
the first pressure.
[0010] In accordance with another aspect of the invention, a method
of forming a thermal energy storage pressure vessel is described.
The method comprises forming a wall having a predetermined height
and thickness, wherein an inner surface of the wall bounds an
interior volume therein. The method further comprises affixing a
reinforcement structure to a surface of the wall at a first
location, affixing at least one additional reinforcement structure
to a surface of the wall at another location along the height of
the wall, and disposing a porous thermal storage medium within the
interior volume.
[0011] In accordance with yet another aspect of the invention, a
thermal energy storage pressure vessel is disclosed, the thermal
energy storage pressure vessel comprising a concrete cylindrical
wall bounding an interior volume, wherein the interior volume is
configured to allow air passage therethrough, and at least one
reinforcing structure affixed to an outer surface of the concrete
cylindrical wall. The thermal energy storage pressure vessel
further comprises a porous thermal matrix material disposed within
the interior volume of the concrete cylindrical wall, wherein the
porous thermal matrix material is configured to allow air passage
therethrough.
[0012] Various other features and advantages will be made apparent
from the following detailed description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The drawings illustrate preferred embodiments presently
contemplated for carrying out the invention.
[0014] In the drawings:
[0015] FIG. 1 is a schematic arrangement of an ACAES system
according to an embodiment of the present invention.
[0016] FIG. 2 is a side view of a TES unit in accordance with an
embodiment of the present invention.
[0017] FIG. 3 is a cross-sectional view of the TES unit of FIG. 2
in accordance with an embodiment of the present invention.
[0018] FIG. 4 is a side view of a TES unit in accordance with an
another embodiment of the present invention.
[0019] FIG. 5 is a cross-sectional view of the TES unit of FIG. 4
in accordance with another embodiment of the present invention.
[0020] FIG. 6 is a cross-sectional view of a TES unit in accordance
with yet another embodiment of the present invention.
DETAILED DESCRIPTION
[0021] According to embodiments of the invention, a system is
provided that comprises a TES unit having at least one reinforced
structure affixed thereto to allow the TES unit to withstand high
pressure and temperature fluctuations.
[0022] First, referring to FIG. 1, a schematic arrangement of the
primary elements of a conventional ACAES system is shown. ACAES
system 100 comprises an electric motor 102 coupled to a
low-pressure compressor 104. Electric motor 102 may be electrically
powered via conventional means, i.e., the utility grid, during
off-peak utility hours. Alternatively, electric motor 102 may be
powered by electricity provided via wind farms, solar arrays, or
other renewable sources. Electric motor 102 powers low-pressure
compressor 104 such that low-pressure compressor 104 pressurizes
intake air 106. Pressurized air 108 from low-pressure compressor
104 is then provided to a high-pressure compressor 112 to enable
the air to undergo further compression. Similar to low-pressure
compressor 104, high-pressure compressor 112 is powered by an
electric motor 110. Electric motor 110 may also be powered by the
utility grid or by renewable sources such as wind farms and solar
arrays. While ACAES system 100 shows the use of two compressors in
a "compression train", it is to be understood that more or fewer
compressors could be used.
[0023] As the air passes through respective low-pressure compressor
104 and high-pressure compressor 112, the air is pressurized to a
level of 65-85 bar and subsequently heated to a temperature of up
to 650.degree. C. This pressurized, heated air 114 then enters a
thermal energy storage (TES) unit 116. TES unit 116 typically
includes a porous thermal storage medium disposed therein, the
porous thermal storage medium capable of retaining a substantial
amount of the heat emitted by air 114 as it passes through TES unit
116. The porous thermal storage medium may be a variety of solid
materials, such as natural stone, ceramics, concrete, cast iron, or
a combination of ceramics and salt. Alternatively, the porous
thermal storage medium may be a liquid material, such as a
combination of nitrate salt and mineral oil.
[0024] After heated air 114 passes through TES unit 116, compressed
air 118 exits TES unit 116 at a lowered temperature to enable
compressed air 118 to be stored in a cavern 122 or other compressed
air storage component. Prior to entering cavern 122, though,
compressed air 118 may need to be further cooled by an optional
intercooler 120 such that compressed air 118 enters cavern 122 at a
maximum temperature of approximately 50.degree. C., for example.
Cavern 122 enables air pressurized to a level of about 60-80 bar to
be stored for an extended period of time without significant
compression losses.
[0025] Referring still to FIG. 1, compressed air 124 may be
discharged from cavern 122 when use of the stored air is desired
for the generation of electricity. Compressed air 124 exits cavern
122 and re-enters TES unit 116 at a temperature of approximately
20-50.degree. C. As the compressed air passes through the porous
thermal storage medium of TES unit 116, it is reheated to a
temperature of up to 600.degree. C., a temperature near that of
heated air 114 previously discharged from high-pressure compressor
112. This reheated compressed air 126, which at this stage is
pressurized to a level of about 55-75 bars, then enters a steam
turbine 128, which is powered by reheated compressed air 126.
Unlike diabatic-CAES systems, compressed air 126 has been reheated
within TES unit 116, and thus there is no need for additional heat
recuperation or gas firing at the steam turbine to reheat the
compressed air. As steam turbine 128 operates, exhaust air 130 is
discharged therefrom, and steam turbine 128 powers an electrical
generator 132. Electrical energy generated by generator 132 may
then be provided to the utility grid for consumption. As can
readily appreciated, ACAES system 100 represents a method of
generating electricity that can greatly reduce, if not eliminate,
natural resource consumption and/or carbon emissions in the
production of electrical energy.
[0026] As discussed above with respect to FIG. 1, TES unit 116 may
be subjected to significant pressures (65-85 bar) and temperatures
(up to 650.degree. C.) during operation of ACAES system 100. As a
result, TES unit 116 is constructed to withstand such high pressure
and temperature levels. Referring to FIGS. 2 and 3, TES unit 116
according to an embodiment of the invention is shown. FIG. 2
illustrates a side view of TES unit 116. TES unit 116 is
illustrated as a cylindrical pressure vessel having a wall 202 of a
predetermined length and thickness. TES unit 116, however, is not
limited to cylindrical shapes, and may be of any suitable shape.
Wall 202 is generally formed of concrete, but may be constructed
using any material of suitable strength and rigidity, such as
steel. Cross section 204 of TES unit 116 further shows that a
plurality of reinforcement structures 206 are affixed to an outer
surface 218 of wall 202 along a length of TES unit 116. While a
plurality of reinforcement structures 206 is shown, it is to be
understood that embodiments of the invention are not limited to the
number and placement of the reinforcement structures 206 shown.
[0027] FIG. 2 further shows a cut-away cross section 208 of TES
unit 116. As can be seen by cut-away cross section 208, each
reinforcement structure 206 comprises at least one rod 210 passing
entirely through an interior volume 212 and wall 202. Interior
volume 212 contains therein a porous thermal storage medium, such
as natural stone or a ceramic material, which is designed to absorb
and retain heat from the compressed air passing through TES unit
116, as described above. Each rod 210 is affixed to an outer
surface of wall 202, thereby providing structural reinforcement
within TES unit 116.
[0028] Referring now to FIG. 3, a cross-sectional view of TES unit
116 according to an embodiment of the invention is shown. As can be
seen in FIG. 3, a plurality of rods 210 are configured to pass
through both wall 202 and interior volume 212, forming a
spoke-shaped framework within interior volume 212. Rods 210 are
preferably made of steel, but may be made of any suitable material
capable of withstanding high pressures and temperatures. Rods 210
are fixedly attached to the outer surface 218 of wall 202 by
anchors 214. Anchors 214 may be affixed to the outer surface 218 of
wall 202 by any appropriate means, e.g., through bolting or
welding. Rods 210 are also coupled at a common centerpoint hub 216
located within interior volume 212. Preferably, rods 210 are of a
sufficient length to pass entirely through wall 202 on opposite
sides thereof and through interior volume 212 and centerpoint hub
216 to be affixed to two opposing anchors 214. For example, as
shown in FIG. 3, a reinforcement structure 206 has four rods 210
interconnected by centerpoint hub 216. Each rod 210 is attached to
outer surface 218 of wall 202 via a pair of respective anchors 214
attached to opposite sides of wall 202.
[0029] According to another embodiment, rather than extending
entirely through wall 202 and interior volume 212 as a single rod,
rods 210 may be configured to pass through wall 202 and extend
toward centerpoint hub 216. In this manner, one end of each rod 210
is retained by a respective anchor 214, while the other end is
retained by or coupled to centerpoint hub 216.
[0030] It is to be understood that the configuration shown in FIG.
3 is merely exemplary and that while four or eight rods 210 are
shown as described above, embodiments of the invention include
using more or fewer rods 210 and anchors 214 in each reinforcement
structure 206.
[0031] By reinforcing TES unit 116 in the fashion shown by FIGS. 2
and 3, wall stresses caused by high air pressure within wall 202
can be substantially relieved. As a result, wall 202 can be
constructed with a reduced overall thickness, as reinforcement
structures 206 act to relieve stress on wall 202 that was
previously addressed through increased wall thickness. With such
reduced wall thickness, TES unit 116 will also not be subject to
the substantial thermal stresses present in pressure vessels having
thick walls. Furthermore, TES unit 116 is easier and less expensive
to both construct and transport over conventional TES units. As
such, embodiments of the invention allow for construction and
adoption of ACAES systems as viable alternatives for producing
electrical energy.
[0032] Referring now to FIGS. 4 and 5, another embodiment of the
present invention is shown. FIG. 4 illustrates a side view of a TES
unit 416 comprising a wall 402 having a predetermined length and
thickness. While TES unit 416 is shown to be cylindrical, it is not
limited as such, and may be of any suitable shape. Wall 402 is
generally formed of concrete, but may be constructed using any
material of suitable strength and rigidity, such as steel. Cross
section 404 of TES unit 416 shows a plurality of reinforcement
structures 406 affixed about an outer surface of wall 402 along a
length of TES unit 416. While FIG. 4 shows a plurality of
reinforcement structures 406 affixed along TES unit 416, the number
and placement of reinforcement structures 406 is not limited to
that shown, as it is possible one or more reinforcement structures
406 affixed to wall 402 according to embodiments of the present
invention.
[0033] FIG. 4 further shows a cut-away cross section 408 of TES
unit 416. Unlike reinforcement structures 206 described above with
respect to FIG. 2, reinforcement structures 406 do not pass through
an interior volume 412 of TES unit 416. Instead, reinforcement
structures 406 comprise a trussed framework 410 that is affixed
along an exterior surface 422 of wall 402. As such, each trussed
framework 410 provides structural reinforcement along exterior
surface 422 of wall 402 of TES unit 416. Interior volume 412, like
interior volume 212 described above with respect to FIGS. 2 and 3,
contains a porous thermal storage medium therein, which is designed
to retain heat from the compressed air passing through TES unit
416.
[0034] FIG. 5 illustrates a cross-sectional view of TES unit 416.
As can be seen in FIG. 5, trussed framework 410 comprises a
plurality of rods 414 affixed to a plurality of anchors 418, the
plurality of rods 414 being further affixed to and bounded by a rim
420. Anchors 418 may be affixed to wall 402 through any known
means, such as by bolt or by weld. Rods 414 and rim 420 may be made
of steel, but are not limited as such, and may be made of any
suitable material. Rods 414 are arranged between anchors 418 and
rim 420 to form the trussed framework about the external surface of
wall 402. It is to be appreciated that the precise number of rods
414 and anchors 418 used is not imperative to the invention, but
the number of rods 414 and anchors 418 utilized should be of an
amount sufficient to allow the trussed framework to pressurize wall
402.
[0035] Using the trussed framework 410 as described above with
respect to the embodiment shown in FIGS. 4 and 5, wall stresses
caused by high air pressure within wall 402 can be substantially
relieved, thereby allowing wall 402 to have a thickness
substantially less than that of conventional TES units. Reduced
wall thickness acts to mitigate the substantial thermal stresses
present in pressure vessels, thermal stresses that become more
prevalent as the walls become thicker. As an additional benefit,
TES unit 416 may be both easier and less expensive to construct and
transport than conventional TES units.
[0036] Next, FIG. 6 illustrates yet another embodiment of the
present invention. FIG. 6 is a cross-sectional view of TES unit
516, which combines the concepts of the spoke-shaped reinforcement
structure of TES unit 116 shown in FIGS. 2, 3 with the external
trussed framework of TES unit 416 shown in FIGS. 4, 5. In
particular, TES unit 516 comprises a plurality of rods 510
configured to pass through both a wall 502 and an interior volume
512, forming a spoke-shaped framework within interior volume 512.
Rods 510 are fixedly attached to the outer surface of wall 502 by
anchors 518 and are coupled at a common centerpoint hub 522 located
within interior volume 512. TES unit 516 further includes a trussed
framework 524 disposed about an outside surface of wall 502. The
trussed framework 524 comprises a plurality of rods 514 affixed to
the anchors 518, the plurality of rods 414 being further affixed to
and bounded by a rim 520. Rods 514 are arranged between anchors 518
and rim 520 to form the trussed framework about the outside surface
of wall 502.
[0037] As can be readily appreciated, the combination of the
spoke-shaped reinforcement structure and the external trussed
framework shown in FIG. 6 provides wall 502 with substantial
protection from pressure-related stresses using walls that are
thinner than walls of conventional TES units. Accordingly, TES unit
516, like TES unit 116 and TES unit 416 described above, can be
constructed to have thinner walls than conventional TES units,
thereby reducing the cost and complexity of constructing the TES
unit, and further reducing the likelihood of thermal stresses being
suffered throughout regular operation of the ACAES system.
[0038] Therefore, according to one embodiment of the invention, a
thermal energy storage system is disclosed, the thermal energy
storage system comprising a pressure vessel configured to withstand
a first pressure, wherein the pressure vessel has a wall comprising
an outer surface and an inner surface surrounding an interior
volume of the pressure vessel. The interior volume of the pressure
vessel has a first end in fluid communication with one or more
compressors and one or more turbines, and a second end in fluid
communication with at least one compressed air storage component. A
thermal storage medium is positioned in the interior volume, and at
least one reinforcement structure is affixed to the outer surface
of the wall, wherein the at least one reinforcement structure
configured to reinforce the wall to withstand a second pressure
greater than the first pressure.
[0039] According to another embodiment of the invention, a method
of forming a thermal energy storage pressure vessel is described.
The method comprises forming a wall having a predetermined height
and thickness, wherein an inner surface of the wall bounds an
interior volume therein. The method further comprises affixing a
reinforcement structure to a surface of the wall at a first
location, affixing at least one additional reinforcement structure
to a surface of the wall at another location along the height of
the wall, and disposing a porous thermal storage medium within the
interior volume.
[0040] According to yet another embodiment of the invention, a
thermal energy storage pressure vessel is disclosed, the thermal
energy storage pressure vessel comprising a concrete cylindrical
wall bounding an interior volume, wherein the interior volume is
configured to allow air passage therethrough, and at least one
reinforcing structure affixed to an outer surface of the concrete
cylindrical wall. The thermal energy storage pressure vessel
further comprises a porous thermal matrix material disposed within
the interior volume of the concrete cylindrical wall, wherein the
porous thermal matrix material is configured to allow air passage
therethrough.
[0041] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *