NZ624443B2 - High efficiency solar receiver - Google Patents
High efficiency solar receiver Download PDFInfo
- Publication number
- NZ624443B2 NZ624443B2 NZ624443A NZ62444312A NZ624443B2 NZ 624443 B2 NZ624443 B2 NZ 624443B2 NZ 624443 A NZ624443 A NZ 624443A NZ 62444312 A NZ62444312 A NZ 62444312A NZ 624443 B2 NZ624443 B2 NZ 624443B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- wing
- tube panel
- assembly
- face
- support
- Prior art date
Links
- 239000003351 stiffener Substances 0.000 claims description 64
- 239000012530 fluid Substances 0.000 claims description 34
- 241000237509 Patinopecten sp. Species 0.000 claims description 20
- 235000020637 scallop Nutrition 0.000 claims description 20
- 238000010521 absorption reaction Methods 0.000 abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 26
- 150000003839 salts Chemical class 0.000 description 25
- 239000011780 sodium chloride Substances 0.000 description 25
- 230000000712 assembly Effects 0.000 description 11
- 230000035882 stress Effects 0.000 description 9
- 238000010276 construction Methods 0.000 description 5
- 230000005611 electricity Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- WYTGDNHDOZPMIW-UHOFOFEASA-O Serpentine Natural products O=C(OC)C=1[C@@H]2[C@@H]([C@@H](C)OC=1)C[n+]1c(c3[nH]c4c(c3cc1)cccc4)C2 WYTGDNHDOZPMIW-UHOFOFEASA-O 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000006011 modification reaction Methods 0.000 description 3
- 239000003973 paint Substances 0.000 description 3
- 210000000614 Ribs Anatomy 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000003247 decreasing Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 230000001681 protective Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S10/00—Solar heat collectors using working fluids
- F24S10/70—Solar heat collectors using working fluids the working fluids being conveyed through tubular absorbing conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S20/00—Solar heat collectors specially adapted for particular uses or environments
- F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
- F24S2080/09—Arrangements for reinforcement of solar collector elements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S40/00—Safety or protection arrangements of solar heat collectors; Preventing malfunction of solar heat collectors
- F24S40/80—Accommodating differential expansion of solar collector elements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
- F28F9/007—Auxiliary supports for elements
- F28F9/013—Auxiliary supports for elements for tubes or tube-assemblies
- F28F9/0132—Auxiliary supports for elements for tubes or tube-assemblies formed by slats, tie-rods, articulated or expandable rods
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/44—Heat exchange systems
Abstract
The present disclosure relates, in various embodiments, to solar receivers (900) that include a central receiver assembly (910) and at least one "wing" assembly. The wing assembly includes a dual-exposure or two-sided heat absorption panel (990), and is supported by structural components extending from the central receiver assembly. The heat absorption panels in the central receiver assembly and in the wing assembly may differ in the design and size of their tubing. Disclosed herein in various embodiments is a solar receiver comprising a central receiver assembly and a wing assembly. The central receiver assembly comprises an internal support structure and at least one external central tube panel (920). rom the central receiver assembly. The heat absorption panels in the central receiver assembly and in the wing assembly may differ in the design and size of their tubing. Disclosed herein in various embodiments is a solar receiver comprising a central receiver assembly and a wing assembly. The central receiver assembly comprises an internal support structure and at least one external central tube panel (920).
Description
HIGH EFFICIENCY SOLAR RECEIVER
BACKGROUND
This application claims priority to U.S. Provisional Patent Application
Serial No. 61/560,631, filed on November 16, 2011. The disclosure of this
application is hereby fully incorporated herein by reference in its entirety.
The present disclosure relates broadly to the field of solar power
generation used to produce electricity. More particularly, this disclosure relates to
a dual-exposure or two-sided heat absorption panel, and a solar receiver including
one or more of such panels. These solar receiver designs can be used with
Concentrated Solar Tower technology, also known as Concentrating Solar Power
(CSP) technology to harness the sun’s energy to produce “green” electricity.
A solar receiver is a primary component of a solar energy generation
system whereby sunlight is used as a heat source for the eventual production of
superheated high quality steam that is used to turn a turbine generator, and
ultimately produce electricity using the Rankine cycle or provide steam for other
thermal processes.
Generally, the solar receiver is positioned on top of an elevated support
tower which rises above a ground level or grade. The solar receiver is
strategically positioned within an array of reflective surfaces, namely a field of
heliostats (or mirrors), that collect rays of sunlight and then reflect and concentrate
those rays back to the heat absorbing surfaces of the solar receiver. This solar
energy is then absorbed by the working heat transfer fluid (HTF) flowing through
the solar receiver. The reflective surfaces may be oriented in different positions
throughout the day to track the sun and maximize reflected sunlight to the heat
absorbing surfaces of the receiver.
The solar receiver is an assembly of tubes with water, steam, molten
salts, or other heat transfer fluid (HTF) flowing inside the tubes. The HTF inside
the tubes of the receiver absorbs the concentrated solar energy, causing the HTF
to increase in temperature and/or change phases, so that the HTF captures the
solar energy. The heated HTF is then either directly routed to a turbine generator
to generate electrical power or is indirectly routed to a storage tank for later use.
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Solar receiver designs typically include an arrangement of panels with
vertically oriented tubes, i.e. tube panels, along with a support structure for
maintaining the tube panels in place and other associated equipment (pumps,
pipes, storage vessels, heat shields, etc.). In conventional designs, the solar
receiver has a square, rectangular, or circular cross-section (in a plan view from
above). The tube panels are arranged on the exterior of the cross-section, so that
the solar energy from the heliostats is directed at (and absorbed by) only one face
of a tube panel. This is illustrated in, for example, U.S. Patent Application Serial
No. 12/605,241, which published as US 2010/0101564 A1 on 29 April 2010, which
is entitled “Shop-Assembled Solar Receiver Heat Exchanger” and is assigned to
Babcock & Wilcox Power Generation Group, Inc., and which is hereby fully
incorporated by reference herein.
In this regard, is a plan view (i.e. viewed from above) of one solar
receiver design 100 discussed above, which has four tube panels 110, 120, 130,
140, arranged as a square. Each tube panel has one exterior face 112, 122, 132,
142 which is exposed to solar energy from heliostats, and one interior face 114,
124, 134, 144 which is not exposed to such solar energy.
The interior non-absorbing face of a tube panel usually has a buckstay
system that supports the tube panels against high wind, seismic forces, and
thermally induced forces. The buckstay system typically includes “I” beams or
other structural steel shapes that are clipped onto the tube panel in such a way
that the tube panel can expand independent of the support structure itself and
independent of the other tubes and panels. Clips are usually welded to the tubes
so that the tube panel can move relative to the stationary support structure when
heat is applied to the tubes, yet the support structure can still provide rigidity to the
tube panel. On a solar receiver, the tubes in the tube panel are not welded
together along their axes (i.e. membrane construction) as in a fossil fuel fired
boiler, but are of loose construction. This allows the tubes to expand
independently of each other when heat is applied. As a result, each tube must
have a clip to attach to the buckstay at a support elevation.
It would be desirable to provide a compact solar receiver that uses a
heat transfer fluid and which is simple in design, modular, and economical.
Additionally or alternatively, it would be desirable to at least provide the
public with a useful choice.
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BRIEF DESCRIPTION
The present invention provides a solar receiver, comprising: a central
receiver assembly comprising an internal support structure and at least one
external central tube panel, the internal support structure defining an interior
volume, the at least one external central tube panel comprising a plurality of
vertical tubes for conveying a heat transfer fluid, wherein the tubes are
interconnected by at least one upper header and at least one lower header, and
being arranged on an exterior face of the internal support structure with the at
least one external central tube panel having an exposed first face and a non-
exposed second face; at least one wing assembly extending from the central
receiver assembly, each wing assembly having a wing tube panel that comprises
a plurality of vertical tubes for conveying a heat transfer fluid, wherein the tubes
are interconnected by at least one upper header and at least one lower header,
and each wing tube panel having a first exposed face and a second exposed face
opposite the first face; and at least one stiffener structure running from a first side
edge to a second side edge across the first exposed face and the second
exposed face of the wing tube panel at a first support elevation, the at least one
stiffener structure formed from a first support assembly on the first face of the
wing tube panel and a second support assembly on the second face of the wing
tube panel, wherein each support assembly includes a support tube, a horizontal
flange extending from the support tube and having a slot therein, and a scallop
bar engaging the tube panel and having at least one lug, the scallop bar engaging
the horizontal flange by a pin passing through the at least one lug and the slot of
the horizontal flange.
The term ‘comprising’ as used in this specification and claims means
‘consisting at least in part of’. When interpreting statements in this specification
and claims which include the term ‘comprising’, other features besides the
features prefaced by this term in each statement can also be present. Related
terms such as ‘comprise’ and ‘comprised’ are to be interpreted in similar manner.
The present disclosure relates, in various embodiments, to solar
receivers that include a central receiver assembly and at least one “wing”
assembly. The wing assembly includes a dual-exposure or two-sided heat
absorption panel, and is supported by structural components extending from the
central receiver assembly. The heat absorption panels in the central receiver
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assembly and in the wing assembly may differ in the design and size of their
tubing.
Disclosed herein in various embodiments is a solar receiver comprising
a central receiver assembly and a wing assembly. The central receiver assembly
comprises an internal support structure and at least one external central tube
panel. The internal support structure defines an interior volume. The at least one
external central tube panel comprises a plurality of vertical tubes for conveying a
heat transfer fluid, wherein the tubes are interconnected by at least one upper
header and at least one lower header. The external central tube panel is
arranged on an exterior face of the internal support structure, with the external
central tube panel having an exposed first face and a non-exposed second face.
The wing assembly extends from the central receiver assembly, each wing
assembly having a wing tube panel. The wing tube panel comprises a plurality of
vertical tubes for conveying a heat transfer fluid, wherein the tubes are
interconnected by at least one upper header and at least one lower header. Each
wing tube panel has an exposed first face and an exposed second face opposite
the first face.
The wing assembly may further comprise a structural support frame, the
structural support frame including: a first vertical column; an upper horizontal
beam extending between an upper end of the first vertical column and an upper
connection on the internal support structure; and a lower horizontal beam
extending from a lower end of the first vertical column to a lower connection on
the internal support structure.
At least one panel support rod may extend between the structural
support frame and the upper header of the wing tube panel.
The solar receiver may further comprise: a first stiffener structure
running from the first side edge to the second side edge across the first face and
the second face of the wing tube panel at a first support elevation. Sometimes, a
second stiffener structure is also present running from the first side edge to the
second side edge across the first face and the second face of the wing tube panel
at a second support elevation.
In embodiments, each stiffener structure is formed from a first support
assembly on the first face of the wing tube panel and a second support assembly
on the second face of the wing tube panel. Each support assembly includes: a
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support tube; a horizontal flange extending from the support tube and having a
slot therein; and a scallop bar engaging the tube panel and having at least one
lug, the scallop bar engaging the horizontal flange by a pin passing through the at
least one lug and the slot of the horizontal flange.
The support tube of each support assembly may have a different
diameter from any tube in the wing tube panel, and in some embodiments is
larger. An outer face of each support tube may be painted to decrease heat
absorption.
In some embodiments, the first support assembly of the first stiffener
structure is fluidly connected to the first support assembly of the second stiffener
structure. The first support assembly of the first stiffener structure can be fluidly
connected to the inlet header of the wing tube panel or fluidly connected to the at
least one external central tube panel. In some other embodiments, the first
support elevation and the second support elevation are not located at a middle
section of the wing tube panel. Additional stiffener structures are contemplated
depending on the height of the two-sided panel.
The central receiver assembly may further comprise an upper heat
shield located above the external central tube panel and a lower heat shield
located below the external central tube panel. The wing assembly may also
further comprise a heat shield having an upper face located above the wing tube
panel, a lower face located below the wing tube panel, and a side face located
distal from the central receiver assembly. An open space can be present between
the side face of the wing assembly heat shield and a side edge of the wing tube
panel. Sometimes, the solar receiver further comprises a horizontal heat shield
located above the external central tube panel.
The upper heat shield, lower heat shield, and wing assembly heat shield
can be painted white to decrease heat absorption. Similarly, the first face and the
second face of the wing tube panel can be painted black to increase heat
absorption.
Each wing tube panel may include a plurality of tube passes, adjacent
tube passes being arranged so that heat transfer fluid flows in a serpentine
manner upward through one tube pass and down through another tube pass.
When the heat transfer fluid is water or steam, the solar receiver may
further comprise a vertical water/steam separator to separate saturated water
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from dry saturated steam for further superheating of the dry steam. Alternatively,
the solar receiver may further comprise a molten salt inlet vessel and a molten salt
outlet vessel, when the heat transfer fluid is molten salt.
The external central tube panel may comprise wall tubes having helical
internal ribs.
In particular embodiments, the internal support structure has a
rectangular cross-section, the central receiver assembly has four central tube
panels, and a total of four wing assemblies extend from corners of the central
receiver assembly.
Also disclosed is a solar energy system, comprising: a solar receiver
having a central receiver assembly and a wing assembly as described above; and
a field of heliostats configured to direct sunlight towards the first face of the central
tube panel, the first face of the wing tube panel, and the second face of the wing
tube panel.
These and other non-limiting aspects of the disclosure are more
particularly described below.
In the description in this specification reference may be made to subject
matter which is not within the scope of the appended claims. That subject matter
should be readily identifiable by a person skilled in the art and may assist in
putting into practice the invention as defined in the presently appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The following is a brief description of the drawings, which are presented
for the purposes of illustrating the exemplary embodiments disclosed herein and
not for the purposes of limiting the same.
is a plan (i.e. top) view of a central receiver assembly design
having a square orientation, with each tube panel having one exterior exposed
face and one interior non-exposed face.
is a first front view of a dual-exposure heat absorption panel that
can be used in the wing assembly of the solar receiver of the present disclosure.
In this figure, heat shields and panel stiffener support structures are removed to
provide an interior view.
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is a second front view of the dual-exposure heat absorption
panel of In this figure, panel stiffener support structures are visible, and
heat shields are removed to provide another interior view.
is an exterior front view of the dual-exposure heat absorption
panel of Here, the heat shields are in place.
is an exterior side view of the dual-exposure heat absorption
panel of
is a plan view showing a portion of a wing tube panel and a
portion of a stiffener structure for the wing tube panel.
is a side cross-sectional view of a portion of a tube panel and a
portion of a stiffener structure for the tube panel as depicted in
is a front view of the portion of a wing tube panel and stiffener
structure as depicted in
is a perspective view of the portion of a wing tube panel and
stiffener structure as depicted in
is an exploded view of a central receiver assembly using a
vertical water/steam separator.
A is a side cross-sectional view of a central tube panel mounted
on the central receiver assembly.
B is a magnified perspective exploded view of the tube panel of
A.
is a schematic diagram of fluid flow through a central receiver
assembly using molten salt as a heat transfer fluid.
is a perspective view of an assembled central receiver
assembly using molten salt as a heat transfer fluid.
is a plan view of a solar receiver of the present disclosure
including a central receiver assembly and a wing assembly.
is an isometric view of the solar receiver of with heat
shields in place.
is a front view of the solar receiver of with heat shields
in place.
is an isometric view of the solar receiver of with heat
shields removed.
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is a front view of the solar receiver of with heat shields
removed.
DETAILED DESCRIPTION
A more complete understanding of the processes and apparatuses
disclosed herein can be obtained by reference to the accompanying drawings.
These figures are merely schematic representations based on convenience and
the ease of demonstrating the existing art and/or the present development, and
are, therefore, not intended to indicate relative size and dimensions of the
assemblies or components thereof.
Although specific terms are used in the following description for the
sake of clarity, these terms are intended to refer only to the particular structure of
the embodiments selected for illustration in the drawings, and are not intended to
define or limit the scope of the disclosure. In the drawings and the following
description below, it is to be understood that like numeric designations refer to
components of like function.
The modifier "about" used in connection with a quantity is inclusive of
the stated value and has the meaning dictated by the context (for example, it
includes at least the degree of error associated with the measurement of the
particular quantity). When used with a specific value, it should also be considered
as disclosing that value. For example, the term “about 2” also discloses the value
“2” and the range “from about 2 to about 4” also discloses the range “from 2 to 4.”
It should be noted that many of the terms used herein are relative
terms. For example, the terms “interior”, “exterior”, “inward”, and “outward” are
relative to a center, and should not be construed as requiring a particular
orientation or location of the structure. Similarly, the terms “upper” and “lower” are
relative to each other in location, i.e. an upper component is located at a higher
elevation than a lower component.
The terms “horizontal” and “vertical” are used to indicate direction
relative to an absolute reference, i.e. ground level. However, these terms should
not be construed to require structures to be absolutely parallel or absolutely
perpendicular to each other. For example, a first vertical structure and a second
vertical structure are not necessarily parallel to each other.
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The term “plane” is used herein to refer generally to a common level,
and should be construed as referring to a volume, not as a flat surface.
To the extent that explanations of certain terminology or principles of
the solar receiver, boiler and/or steam generator arts may be necessary to
understand the present disclosure, the reader is referred to Steam/its generation
and use, 40th Edition, Stultz and Kitto, Eds., Copyright 1992, The Babcock &
Wilcox Company, and to Steam/its generation and use, 41st Edition, Kitto and
Stultz, Eds., Copyright 2005, The Babcock & Wilcox Company, the texts of which
are hereby incorporated by reference as though fully set forth herein.
The present disclosure relates to solar receivers that include a central
receiver assembly and at least one “wing” assembly. The wing assembly includes
a dual-exposure or two-sided heat absorption panel, and is supported by
structural components extending from the central receiver assembly. The heat
absorption panels in the central receiver assembly and in the wing assembly may
differ in the design and size of their tubing.
The two-sided heat absorption panels in the wing assembly are
designed to accept heat on two opposite sides or faces, rather than on only one
side or face. This feature results in tube temperatures on the two opposite faces
of the wing assembly that are more closely balanced than tube panels which are
heated on only one side and therefore have an imbalanced tube temperature from
the hot side (heat absorbing side) to the cold side (non-heat absorbing side) of the
tubes. The temperature balance across the two opposite faces of the wing panel
tubes reduces thermal stresses and thus can reduce tube failures due to fatigue
and/or stress corrosion. In addition, the available heat absorbing area on the wing
assembly is doubled compared to the heat absorbing area on the central receiver
assembly, which can only absorb heat on one side The combination of doubled
heat absorbing area and reduced thermal stresses results in wing panels that can
absorb more than twice as much heat as single-sided heating panels. This
significantly improves collector surface efficiency. Desirably, it is contemplated
that such technology can ultimately reduce the levelized cost of electricity (LCOE)
by reducing pressure part quantity and/or receiver quantity, and by increasing
plant efficiency by reducing solar receiver thermal losses and providing a more
optimal target for heliostat pointing.
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The panels may include one or more stiffener structures or heat shields.
Generally, the solar receiver is located at the top of a vertical support structure
which rises above a ground level or grade. The vertical support structure may be
supported from a base. The heat transfer surfaces advantageously comprise
loose tangent tube panels, which allows for unrestrained thermal expansion of the
tubes / tube panels in both the horizontal and vertical directions, thereby
eliminating additional tube stresses. As is known to those skilled in the art, the
sizes of tubes, their material, diameter, wall thickness, number and arrangement
for the heat transfer surfaces are based upon temperature and pressure for
service, according to applicable design codes. Required heat transfer
characteristics, circulation ratios, spot absorption rates, mass flow rates of the
working fluid within the tubes, etc. are also important parameters which must be
considered. Depending upon the geographic location where the solar receiver is
to be installed, applicable seismic loads and design codes are also considered.
It should be noted that in some embodiments, molten salt is used as the
heat transfer fluid (HTF) that is run through the absorption panel. In this regard,
molten salt solidifies at approximately 430°F (221°C, 494°K). When the tube
panel(s) of the solar receiver is not exposed to light/heat, either intentionally at
shutdown or unexpectedly due to a heliostat field malfunction, the molten salt can
quickly cool and form plugs. Plugged tubes can cause delays at start up and
could lead to tube failures. Thus, the ability to drain molten salt quickly is typically
part of the solar receiver design. The valves and additional piping for such
draining may not be depicted herein, but should be considered as being present.
The present disclosure also contemplates the use of water, steam, or any other
heat transfer fluid, with appropriate modifications made to other components of
the solar receiver.
Initially, the components of the wing assembly and the central receiver
assembly are described separately. FIGS. 2-4 are various front views of a wing
assembly containing a dual-exposure or two-sided heat absorption panel, differing
in the presence or absence of certain structures and allowing for a better
comprehension of the present disclosure.
In a two-sided heat absorption panel 200 is visible. The
absorption panel 200 includes a tube panel 210. The tube panel 210 has a first
exposed face 222 and a second exposed face 224 (not visible; see
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opposite the first exposed face. The term “exposed” refers to the fact that
concentrated sunlight from heliostats can be directed against the face of the tube
panel. The first face 222 and second face 224 may also be referred to as exterior
faces, which also refers to their being able to receive concentrated sunlight from
heliostats. The first face and the second face are generally planar surfaces. The
tube panel 210 extends between an upper header 242 and a lower header 250.
Put another way, the tubes in the tube panel are interconnected by at least one
upper header and at least one lower header. It should be noted that in practice,
the tube panel may include multiple upper headers and lower headers. The tube
panel 210 also has an upper edge 212, a lower edge 214, a first side edge 216,
and a second side edge 218. It should be noted that in this view, one can see
through the structure between the tube panel 210 and the structural support frame
300.
A structural support frame 300 runs around the upper edge 212, the
lower edge, the first side edge 216, and the second side edge 218 of the wing
tube panel. The structural support frame 300 includes a first vertical column 310,
a second vertical column 320, an upper horizontal beam 330, and a lower
horizontal beam 380. The upper horizontal beam 330 extends between an upper
end 312 of the first vertical column and an upper end 322 of the second vertical
column. The lower horizontal beam 380 extends between a lower end 314 of the
first vertical column and a lower end 324 of the second vertical column.
As seen here, the first vertical column 310 is adjacent the first side edge
216, the second vertical column 320 is adjacent the second side edge 218, the
upper horizontal beam 330 is adjacent the upper edge 212 of the wing tube panel,
and the lower horizontal beam 380 is adjacent the lower edge 214 of the wing
tube panel. The wing tube panel 210 is connected to the structural support frame
300 through the upper header 242. Here, the wing tube panel is top supported.
At least one panel support rod 202 extends between the structural support frame
300 and the upper header 242; three such panel support rods are shown here.
Generally, a wing tube panel 210 requires at least one tube pass 240,
an upper header 242, and a lower header 250. HTF flows from the inlet header to
the outlet header (e.g. here the upper header can be the inlet header) and is
heated in the tube pass by solar energy from heliostats. Each tube pass 240
includes at least one tube, and generally includes a plurality of such tubes. In
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the wing tube panel is shown with a plurality of tube passes (here four).
The tube panels and tube passes contemplated herein are of loose tube
construction to allow independent differential expansion between tubes, reducing
tube stresses. The exposed faces of the tubes may be coated or painted to
increase/maximize heat absorption, for example with a special high temperature
black paint. Adjacent tube passes are arranged so that heat transfer fluid flows
upward through one tube pass and down through another tube pass in a
serpentine manner. Various fluid flow arrangements may be used to facilitate
draining of the HTF and minimize the number of vent and drain valves. Arrows
here illustrate one such fluid flow arrangement.
In two stiffener structures are shown. Each stiffener structure
preferably runs from the first side edge 216 to the second side edge 218 across
the first face 222 and the second face 224 of the tube panel. Here, a first stiffener
structure 401 is located at a first support elevation 225 and a second stiffener
structure 402 is located at a second support elevation 226. The two stiffener
structures are arranged in parallel. As explained further below, each stiffener
structure is formed from two support assemblies, one support assembly on each
face of the tube panel. Each support assembly includes a support tube. Here,
support tube 400 is visible on this first face. The support tube 406 provides
stiffener structures on the second face.
Generally, the number of stiffener structures can depend on the
maximum unsupported length of the wing tube panel that will resist wind and
seismic loads. In this regard, the wing tube panel 210 can be considered as being
divided into an upper section 230, a middle section 232, and a lower section 234,
which generally (but not necessarily) divide the exposed portion of the wing tube
panel into equal sections along its height. The first stiffener structure 401 is
shown in the upper section 230, and the second stiffener structure 402 is shown in
the lower section 234. Put another way, the stiffener structures are typically not
located in the middle section. This keeps the stiffener structures out of the peak
heat flux zone and reduces their operating temperatures. It is contemplated that
the stiffener structures will include support tubes that will be cooled by some heat
transfer fluid, which could be the same as or different from the HTF that is passed
through the wing tube panel. For example, the use of oil or water can eliminate
the potential for molten salt freezing in the stiffener structure during startup and
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shutdown. Here, the stiffener structures are illustrated as being formed in part by
a support tube 400 which is connected to the upper header 242 and lower header
250, which uses the same HTF as that passing through the tube panel 210. The
stiffener structures 401, 402 are the portions of the support tube 400 that run
across the face 222 of the tube panel 210. The circuitry is ultimately designed to
minimize temperatures and stresses, allow independent thermal expansion of the
stiffener structure, and minimize the potential for freezing of fluid during startup.
The outer face of the stiffener structure can be painted or coated to
reduce/minimize heat absorption.
In the structural support frame (not visible; see is shown
with heat shields mounted to protect certain parts of the design from exposure to
the concentrated sunlight coming from the heliostats. The structural support
frame 300 is not visible in but is visible in Here, a first heat shield
340 frames the first face 222 of the wing tube panel 210. A second heat shield
360 (not visible; see also frames the second face 224 of the wing tube
panel. In this regard, the heat shield 340 includes an interior edge 342 that forms
a window in the heat shield through which the wing tube panel 210 is visible. The
heat shield 340 can be considered as including an upper face 352, a first side face
354, a second side face 356, and a lower face 358. Dotted lines show the outline
of the wing tube panel 210, the upper header 242, and the lower header 250. As
seen here, the interior edge 342 of the heat shield abuts the side edges 216, 218
of the wing tube panel, but could also be arranged with a gap or open space
between the heat shield and side edges of the tube panel to allow more solar
energy on the edge of the panel while reducing spillage onto the heat shields.
Each heat shield 340, 360 could also be considered as having an upper face, a
first side face, a second side face, and a lower face. The first heat shield and the
second heat shield are generally made from a heat-resistant material. The heat
shield(s) can also be coated or painted with a reflective high temperature white
paint to decrease/minimize heat absorption and/or operating temperature.
is an exterior side view of the wing assembly. The first heat
shield 340 and the second heat shield 360 are visible here. The exposed first
face 222 and second face 224 are also indicated. The base 302 of the structural
support frame and the apex 304 of the structural support frame are also indicated.
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It should be noted that a heat shield 370 is also present on the sides of the
structural support frame 300.
As noted in stiffener structures are used to support and
strengthen the tube panel. FIGS. 6-8A are different views of one exemplary
embodiment of a stiffener structure. is a plan (i.e. top) view of the
exemplary embodiment. is a side cross-sectional view of the exemplary
embodiment. is a front view of the exemplary embodiment. is a
perspective view.
Referring to the stiffener structure 401 is formed from a first
support assembly 410 and a second support assembly 470, which are located on
the opposite exposed faces of the tube panel. (Referring back to the first
support assembly 410 is part of the support tube 400, and the second support
assembly 470 is part of the support tube 406.) Each support assembly 410
includes a support tube 420, horizontal flange 430, and scallop bar 440. The
support tube 420 is contemplated to be hollow and allow a cooling fluid to pass
through. A horizontal flange 430 extends from the support tube inwards towards
the tube panel 210. The horizontal flange 430 has a slot 432 therein. As seen
here, the horizontal flanges 430, 472 on the two support assemblies are opposed
to each other. The scallop bar 440 has a contoured face that engages the tube
panel 210, and lugs 448 on an opposite face. The scallop bar is connected to the
support tube by a pin 450 which passes through the lugs 448 and the slot 432.
The scallop bar is held snug (but not fixed) against the panel tubes 460 with pins
452 that pass through lugs 454 that are welded to some of the panel tubes, and
the scallop bar engages one or more of the tubes. The lugs 454 holding the
scallop bar 440 between the tubes 460 and pins 452 are offset from the lug 448
connecting the scallop bar 440 to the support tube 420. This allows the panel
tubes and scallop bars to thermally expand in unison in the vertical direction,
independent of the relatively stationary (in the vertical direction) support assembly.
A protective sleeve 446 can be placed between the panel tube and the scallop bar
as shown to protect the tubes from wear and/or gouging if any relative motion
(sliding contact) occurs between the scallop bar and panel tubes. It is noted that
only one pair of flanges and lugs 430, 478 is depicted here, but additional flanges
and lugs may be present on each support assembly to resist panel twisting and
maintain panel-to-panel alignment. Similarly, only one scallop bar 440 is shown
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attached to support tube 420, but multiple scallop bars could be used along the
support tube to stiffen a single wide panel or multiple panels, for example, if there
is a significant difference in vertical thermal expansion between tubes within a
panel or between panels, as desired. Also, each scallop bar 440 could have
multiple lugs 448. The stiffener structure can be supported by the structural
support frame (see . The support tubes can be attached or connected to
the vertical columns of the support frame, though they are not shown here as
such.
The stiffener structure allows for independent thermal expansion of the
individual tubes in the wing tube panel, as well as for independent thermal
expansion of the stiffener structure and the support tubes. The pin/slot
arrangement between the scallop bar and the support tube permits the support
tubes to thermally expand axially independently of the radial expansion of the
tubes in the wing tube panel. (Note the axis of the support tube is horizontal and
perpendicular to the vertical axis of the tubes in the wing tube panel.)
The support system described above allows the individual tubes 460 to
be arranged in a tangent tube fashion with minimal gap between the tubes. This
reduces energy loss from light passing through the gaps and therefore increases
receiver heat absorption and efficiency. The individual tubes 460 are seen here
with their centers 462 along the midline 405 of the tube panel. Other variations on
the tube layout are also contemplated.
Referring now to in some embodiments, the support tube 420 of
the support assembly could have a different diameter 425 from the diameter 465
of any tube 460 in the tube panel to provide the support tubes with additional
stiffness and in order to stiffen the panel and shade the parts associated with the
support assembly, thus reducing part operating temperatures. In some
embodiments, the support tube diameter 425 is larger than the diameter 465 of
any tube 460 in the tube panel. The support tube 420 can also be considered as
having an inner face 422 and an outer face 424, the outer face being exposed to
reflected sunlight from the heliostats. The outer face 424 of the support tube can
be coated or painted to decrease/minimize heat absorption and/or operating
temperature.
Referring to at least three variations on the stiffener structures
are specifically contemplated. First, the support tubes 400, 406 that make up the
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stiffener structures 401, 402 are illustrated as being connected to the upper
header 242 and the lower header 250, so that they use the same HTF as flows
through the tube panel 210. However, other embodiments are contemplated in
which the support tubes use a different cooling fluid. This could be accomplished,
for example, by connecting the support tubes to separate headers. Second,
support tube 400 is illustrated here as contributing the support assembly to both
stiffener structures 401, 402. In other embodiments, the stiffener structures could
be made using separate support tubes. For example, a support tube could run
across the first support elevation 225, but would not run back across the second
support elevation 226; a different support tube could be used for the stiffener
structure at the second support elevation if necessary. Third, as illustrated here a
stiffener structure 401 uses two separate support tubes 400, 406. Other
embodiments are contemplated where only one support tube is used for the
stiffener structure. This could be done, for example, by forming the support tube
as a rectangular torus that surrounds the tube panel. This single support tube
would provide the stiffener structure 401 adjacent to the first face of the panel and
then wrap around the panel at the same elevation and provide the stiffener
structure adjacent to the opposite face of the tube panel. This could be done at
the second stiffener structure elevation 402 also by the same support tube or a
different support tube.
It is also noted that in each support tube connects to the upper
header and the lower header on the same side of the tube panel. For example,
support tube 400 connects to both the upper header 242 and the lower header
250 along first side edge 216. It should be understood that this may differ. For
example, if only one stiffener structure is present, support tube 400 could connect
to the upper header 242 along first side edge 216, then cross the first face and
connect to the lower header along second side edge 218.
As discussed above, the solar receivers of the present disclosure
include a wing assembly and a central receiver assembly. Some different central
receiver assemblies are now described.
is an exploded cross-sectional view of the various components of
one exemplary embodiment of the central receiver assembly. In this exemplary
embodiment, it is contemplated that the heat transfer fluid (HTF) is steam and
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water. Generally, the central receiver assembly 800 has an internal support
structure 810 and at least one central tube panel 820.
The internal support structure 810 depicted here has a rectangular
shape when viewed from the side and a square shape when viewed from above
(i.e. a plan view). The internal support structure 810 here is assembled from four
vertical pylons 812 and three elevations of buckstays 814 arranged horizontally
between the pylons. The vertical pylons are attached to a base 816. The internal
support structure 810 defines an interior volume 811 in which components of the
solar receiver can be located and not exposed to concentrated sunlight. For
example, here a vertical steam/water separator 802 is located within the interior
volume 811. The interior volume 811 is protected from concentrated sunlight by
the exterior tube panels and by barriers that block light that passes between the
tangential, loose tubes. Access platforms 818 are shown here at two levels to
provide access to the volume of the internal support structure.
The solar receiver depicted here has two different sets of central tube
panels 820, which serve as evaporator tube panels 822 and superheater tube
panels 824. Each central tube panel 820 extends between an upper header 826
and a lower header 828. The vertical steam/water separator 802 is structurally
and fluidly interconnected to the tube panels 822, 824. The internal support
structure 810 supports the vertical steam/water separator 802 and the central tube
panels 820. The central tube panels 820 are mounted to the internal support
structure 810 at the buckstays 814.
As depicted here, each side of the solar receiver 800 comprises one
evaporator tube panel 822 and one superheater panel 824. Two primary
superheater (PSH) panels 824 form one corner of the central receiver assembly
800 and two secondary superheater (SSH) panels 824 form an opposite corner
(not shown). To allow for flexibility of the tubes, the evaporator panels 822 and
superheater panels 824 are typically constructed of closely spaced tangent loose
tubes (no membrane) with generous tube bends near the headers for additional
flexibility. The tubes can be small-diameter thin-wall tubes to minimize hot-to-cold-
side and through-tube-wall temperature differentials and thermal stress. The tube
panels can thermally expand in both the horizontal and vertical directions, thereby
minimizing tube stresses. Other arrangements of the evaporator tube panels 822
and superheater panels 824 are also contemplated. For example, the evaporator
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panels 822 and superheater panels 824 may not be placed on every side, or the
superheater panels 824 may not meet at a corner, or there may even be different
configurations of plural evaporative 822 and superheater panels 824 provided on
a given side.
The upper headers 826, lower headers 828, and other components are
protected from spillage and stray light energy by heat shields that extend around
the perimeter of the central receiver assembly 800. An upper heat shield 840 is
located above the central tube panels 820, and a lower heat shield 842 is located
below the central tube panels 820. The exposed side of the heat shields can be
painted white to reduce operating temperatures. The back side of the heat shields
is typically not insulated to reduce operating temperatures. A gap may also be
present between the heat shields 840, 842 and the central tube panels 820 to
allow natural air flow for additional cooling.
An explanation of the fluid flow may be helpful in explaining the
connections between the various components. The central receiver assembly 800
is designed for natural circulation and does not require a circulating pump, though
one may be provided. Feedwater enters the vertical separator 802 near mid height
of the receiver 800. This relatively cool water flows downwards through a
downcomer pipe (not shown) at the bottom of the vertical separator. Supply pipes
850 carry the water from the downcomer pipe to the lower headers of the
evaporator panels 822. The solar energy/heat from the heliostats is absorbed by
the water flowing upward though the tubes in the evaporator panels 822, which is
lower in density than the water leaving the vertical separator 802, resulting in a
natural pumping action. The water-steam mixture exits the headers at the top of
the evaporator panels 822. Risers 852 carry the water-steam mixture to the
vertical separator 802, which separates the mixture into water and dry saturated
steam. The water removed flows downward in the vertical separator 802 for
recirculation.
The dry saturated steam leaves the top of the vertical separator 802
and flows through saturated steam piping 854 to inlet headers at the top of the
primary superheater panels 824. Steam flows through the tube passes of the
primary superheater panels 824 in parallel, starting adjacent the evaporator
panels 822. This arrangement puts the coldest steam next to the evaporator
panels 822 to protect the superheater panels 824 from spillage during startup. As
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the steam flows through the primary superheater panels, solar energy/heat from
the heliostats is absorbed by the steam in order to raise the temperature above
saturation. Steam then exits the primary superheater panels 824, mixes and flows
though the attemperator 856 and associated piping 858, then splits and enters
secondary superheater panels (not visible) at the top. The secondary superheater
panels are located on an opposite corner of the central receiver assembly 800.
Similar to the primary superheater, steam flows through the tube passes of the
secondary superheater panels in parallel, starting adjacent the evaporator panels.
This arrangement puts the coolest steam of the secondary superheater next to the
evaporator panels to protect the superheater panels from spillage during startup.
As the steam flows through the passes of the secondary superheater, solar
energy/heat from the heliostats is absorbed by the steam in order to further raise
the temperature. The final superheated steam can leave the central receiver
assembly 800 (and the solar receiver) via a main steam pipe (not shown).
A is a side view of a central tube panel 820 which utilizes one
sided heat absorption, and B is an enlarged perspective exploded view of
the central tube panel. A reflective modular panel light barrier 836 is located
behind the tubes 830 (i.e. the non-exposed face of the central tube panel)
opposite the heat absorbing (i.e. exterior) side of the tube panel. This light barrier
is designed to protect the insulation 838, support structure 810, and the interior
parts of the solar receiver from rain and heat exposure that may travel through the
gaps between the loose tangent tubes of the tube panels. The modular design of
the light barrier simplifies removal for inspections and/or maintenance. The light
barrier 836 is composed of an array of metal sheets and may be coated with white
paint or other reflective material on the tube side to maximize reflectance of light
energy back to the tubes and reduce operating temperatures of the barrier plate.
The light barrier is supported by the tube attachment structure, i.e. the buckstay
support system 814. Behind the light barrier (i.e. further interior of the solar
receiver) is the insulation 838, which is covered by lagging.
Alternatively, in another exemplary embodiment of the solar receiver it
is contemplated that the heat transfer fluid (HTF) is molten salt. is a
schematic diagram illustrating fluid flow through the central receiver assembly 800
using molten salt. In this diagram, the fluid flows through two sides (i.e. two tube
panels 884, 886) of the solar receiver. A second parallel and independently
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controlled flow path through the other two sides of the receiver is not shown but is
identical. Initially, a riser 870 provides cold molten salt to a molten salt inlet vessel
860 from cold storage tank 801. For example, “cold” molten salt may be pump
from the cold storage tank having a temperature of about 550°F. An inlet pipe 872
fluidly connects the inlet vessel 860 to a first tube panel inlet 874. The jumper
pipes 896 between tube passes is also illustrated. The first tube panel outlet 876
is fluidly connected to a second tube panel inlet 878 through a crossover pipe 875.
An outlet pipe 882 fluidly connects the second tube panel outlet 880 to a molten
salt outlet vessel 862. The HTF can flow from the inlet vessel 860 through the first
tube panel 884 and the second tube panel 886 to the outlet vessel 862. A
downcomer pipe 888 leads from the outlet vessel 862 back down to grade, where
the “hot” fluid can flow into hot storage tank 803.
The outlet pipe 882 and outlet vessel 862 are optional and not required,
which is indicated by dotted line. Without an outlet vessel, the HTF flows from the
second tube panel outlet 880 directly to the downcomer pipe 888 via outlet pipe
891. A bypass line 890 also connects the riser 870 to the downcomer pipe 888. If
desired, this bypass flow path can prevent the HTF from flowing through the tube
panels 884, 886.
This completes the energy collection process. The stored thermal
energy in the heat transfer fluid can be used to generate steam and electricity.
This is done by, for example, pumping the hot HTF from the hot storage tank 803
through the shell side of a heat exchanger 805. Water enters the tube side of
heat exchanger 805 and is converted to steam. The steam can be sent to turbine
807, which drives an electrical generator 809. The cooler HTF leaving the heat
exchanger then returns to the cold storage tank 801, where it is pumped to the
receivers to repeat the energy collection process described above.
For a molten salt receiver, the tube panels must be fully drainable and
ventable. The receiver is usually drained when not in use, at sunset, or when
available solar energy is too low. Molten salt solidifies at approximately 430°F
(221°C, 494°K). If not drained, the salt can freeze inside the tubes, plug the
receiver, and could rupture the tubes. As seen here, the solar receiver can
include a vent valve 892 for each independent flow path which are both vented
through the top of the downcomer pipe 888. The vent valve is typically located
near the top of the downcomer pipe 888, and the vent piping 894 is also illustrated
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connecting the flow path to the downcomer pipe. One drain valve 897 is typically
provided for each pair of tube panels, and are located beneath the tube panels.
The drain piping 898 is also illustrated, and connects to the downcomer 888 so
that molten salt present in the tube panels drains and flows into the downcomer
pipe 888. The vent valves and drain valves are automated.
It should be noted that in , the various pipes are illustrated as
being relatively straight fluid paths. However, it will be appreciated by those
skilled in the art that their actual design in terms of arrangement and length will be
determined by the degree of flexibility required to accommodate expected motions
caused by thermal expansion and contraction during operation of the solar
receiver. It is thus likely that additional bends or length may be necessary to
provide such flexibility.
is a perspective view of an assembled central receiver
assembly that uses molten salt. At the bottom, the riser 870 enters the inlet
vessel 860. The molten salt inlet vessel 860 is located below the optional outlet
vessel 862. The inlet vessel 860 is also located below the central tube panels
820. Put another way, the central tube panels 820 are located (both structurally
and fluidly) between the inlet vessel 860 and the optional outlet vessel 862. The
downcomer 888 is also visible. An upper oven box 864 encloses the upper
headers of the central tube panels 820. A lower oven box 866 encloses the lower
headers of the central tube panels 820. In this regard, the oven boxes use electric
heater elements to preheat the areas of the central tube panels 820 that are not
exposed to concentrated solar heat flux prior to filling. Preheating is necessary at
startup to ensure that all metal which comes in contact with the HTF is heated to
at least the temperature associated with the cold HTF prior to introduction of the
HTF through the central receiver assembly 800. The upper heat shield 840 is
located above the upper headers of the central tube panels 820 and above the
upper oven box 864. The lower heat shield 476 is located below the lower
headers of the central tube panels 820 and below the lower oven box 866. At the
top of the central receiver assembly, the internal support structure 810 is visible,
as is the optional outlet vessel 862.
FIGS. 13-17 illustrate various views of an exemplary embodiment of a
solar receiver of the present disclosure. The solar receiver includes a central
receiver assembly and at least one wing assembly. Generally, there is one wing
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assembly for each corner of the central receiver assembly. In the depicted
embodiment, the central receiver assembly has a square shape and there are four
wing assemblies.
is a plan view of the solar receiver 900 showing the tube panels
920 in the four-sided central receiver assembly 910 and four wing assemblies
930, with supporting structures removed. The four sides of the central receiver
assembly are central tube panels 920 having an exposed first face 922 on the
exterior and a non-exposed second face 924 on the interior of the central receiver
assembly. An interior volume 911 is present in the central receiver assembly. A
wing assembly 930 extends from each corner 913 of the central receiver
assembly. A wing assembly in this four-sided configuration is perpendicular to
adjacent wing assemblies. Generally, the central receiver assembly could be any
n-sided polygonal shape with any quantity of wing assemblies.
is an isometric side view of the solar receiver with the heat
shields in place. is a front view of the solar receiver with the heat shields
in place. The central receiver assembly 910 has an upper heat shield 912 located
above the central tube panel 920, and a lower heat shield 914 located below the
central tube panel. A heat shield 960 frames each exposed face 992, 994 of the
wing tube panel 990. The heat shield 960 can be considered as including an
upper face 962, a lower face 964, and a side face 966. The side face 966 of the
wing assembly heat shield is located distal from the central receiver assembly. A
side heat shield 970 on the side of the wing assembly 930 is also visible.
Referring to , an inner open space 932 is visible between the
central tube panel 920 and the wing tube panel 990, and no heat shield is present
in this area. An outer open space 934 is also present between the side face 966
of the wing assembly heat shield and the side edge 995 of the wing tube panel.
These open spaces create a free-standing wing tube panel. This arrangement
allows the heliostats to be focused more uniformly across the width of the wing
tube panel, which generally requires some heliostats to be focused towards the
edges. The open spaces provide a buffer that reduces spillage of concentrated
sunlight upon the heat shields. The concentrated sunlight can pass through the
open space from one side of the wing tube panel to the other side. However, it is
possible that the concentrated sunlight passing through will hit another tube panel
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on the solar receiver, depending on the orientation and direction of the
concentrated sunlight.
A horizontal heat shield 915 is located above the central tube panel 920
as well, and extends to the distal end 936 of the wing assemblies. The horizontal
heat shield 915 is located at an elevation that frames the central tube panel, or
along the inside edge 968 of the wing assembly heat shield (see ). The
upper heat shield 912 of the central receiver assembly, the lower heat shield 914
of the central receiver assembly, and the heat shield 970 of the wing assembly
can all be coated/painted to reduce/minimize heat absorption. The exposed first
face 992 and exposed second face 994 of the wing tube panel 990 can be
coated/painted to increase/maximize heat absorption, as can the first exposed
face 922 (see ) of the central tube panel 920.
is an isometric side view of the solar receiver with the heat
shields removed to reveal some of the underlying structure. is a front
view of the solar receiver with the heat shields removed.
The embodiment depicted here is a steam/water solar receiver with
water as the HTF, so a vertical steam/water generator 901 is included (see ). The internal support structure 904 of the central receiver assembly is also
visible, and extends above the tube panels. The structural support frame 940 for
the wing assembly depicted here includes a first vertical column 942 at a distal
end 936. An upper horizontal beam 948 extends from an upper end 944 of the
first vertical column to an upper connection on the internal support structure
(reference numeral 908). A lower horizontal beam 950 is located below the wing
tube panel, and extends from a lower end 946 of the first vertical column to a
lower connection (reference numeral 956) on the internal support structure 904.
As shown here, the lower horizontal beam is connected but not fixed to the
internal support structure to allow for differential thermal expansion; however,
other such embodiments are contemplated. The upper horizontal beam 948 and
lower horizontal beam 950 are generally parallel to each other, though this is not
required.
Also visible in and is a first stiffener structure 980 and a
second stiffener structure 984, which are located at a first support elevation 991
and a second support elevation 993 on the wing tube panel. These stiffener
structures are like that described in FIGS. 6-8A, and the first support assembly
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982, 986 of each stiffener structure is visible. It should be noted that here, the first
support assembly 982 of the first stiffener structure is fluidly connected to the first
support assembly 986 of the second stiffener structure through an intermediate
pipe 903. In addition, the first support assembly 982 of the first stiffener structure
is fluidly connected to the upper header 996 of the wing tube panel through an
inlet pipe 902. The first support assembly 986 of the second stiffener structure is
fluidly connected to the lower header 998 of the wing tube panel through an outlet
pipe 905. In this regard, heat transfer fluid can flow through the support tube of
the support assembly to cool the support assembly. Alternatively, the support
assemblies of either stiffener structure can be fluidly connected a central tube
panel on the central receiver assembly.
Because this depicted embodiment is a steam/water solar receiver with
water as the HTF, saturation piping 906 is visible extending from the top of the
vertical separator 901 to the upper headers 996 of the wing tube panels. In this
regard, the central tube panels are being used as evaporator panels to convert
water into a water/steam mixture. The wing tube panels are then used as
superheater panels. Alternatively, the central tube panels could be used as
superheater panels, and the wing tube panels used as evaporator panels. A
molten salt solar receiver would be arranged similarly but there would not be a
vertical separator, and salt piping would connect the wing panels to the central
tube panels.
It should be noted that the construction of the central tube panels can
differ from the construction of the wing tube panels. In particular embodiments
such as steam/water solar receivers, the tubes in the central tube panel may have
helical internal ribs, or in other words helical internal ribbed tubing may be used
for the central tube panel, particularly when these panels are used as evaporator
panels. This allows a higher heat input in the central tube panels, which are
heated on only one side, which increases the maximum practical heating
efficiency. This allows the solar receiver to be designed for either natural or
forced circulation with incident heat fluxes that can be two or three times greater
compared to smooth bore tubes. Alternatively, coil-spring wire inserts, twisted
tape inserts, longitudinal internal fins, porous surface coatings, machined surface
features, or any other internal flow heat transfer enhancement scheme could be
used in the tubes of the central tube panel. Such enhancements are not used on
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the wing tube panel because it is already exposed to twice the concentrated
sunlight and can absorb the increased heat flux due to reduced thermal stresses
(due to exposure on both faces). The resulting solar receiver can obtain
significantly higher efficiency in capturing the available solar energy, allowing the
size of the overall solar receiver to be decreased while still capturing the same
total amount of solar energy, or allowing a receiver of equivalent size to capture
more solar energy.
The present disclosure has been described with reference to exemplary
embodiments. Obviously, modifications and alterations will occur to others upon
reading and understanding the preceding detailed description. It is intended that
the present disclosure be construed as including all such modifications and
alterations insofar as they come within the scope of the appended claims or the
equivalents thereof.
6355800_3.docx
Claims (9)
1. A solar receiver, comprising: a central receiver assembly comprising an internal support structure and at least one external central tube panel, the internal support structure defining an interior volume, the at least one external central tube panel comprising a plurality of vertical tubes for conveying a heat transfer fluid, wherein the tubes are interconnected by at least one upper header and at least one lower header, and being arranged on an exterior face of the internal support structure with the at least one external central tube panel having an exposed first face and a non- exposed second face; at least one wing assembly extending from the central receiver assembly, each wing assembly having a wing tube panel that comprises a plurality of vertical tubes for conveying a heat transfer fluid, wherein the tubes are interconnected by at least one upper header and at least one lower header, and each wing tube panel having a first exposed face and a second exposed face opposite the first face; and at least one stiffener structure running from a first side edge to a second side edge across the first exposed face and the second exposed face of the wing tube panel at a first support elevation, the at least one stiffener structure formed from a first support assembly on the first face of the wing tube panel and a second support assembly on the second face of the wing tube panel, wherein each support assembly includes a support tube, a horizontal flange extending from the support tube and having a slot therein, and a scallop bar engaging the tube panel and having at least one lug, the scallop bar engaging the horizontal flange by a pin passing through the at least one lug and the slot of the horizontal flange.
2. The solar receiver of claim 1, wherein the wing assembly further comprises a structural support frame, the structural support frame including: a first vertical column; an upper horizontal beam extending from an upper end of the first vertical column to an upper connection on the internal support structure; and 6355800_3.docx a lower horizontal beam extending from a lower end of the first vertical column to a lower connection on the internal support structure.
3. The solar receiver of claim 1, wherein the support tube of each support assembly has a larger diameter than any tube in the wing tube panel.
4. The solar receiver of claim 1, wherein the first support assembly of the first stiffener structure is fluidly connected to an inlet header of the wing tube panel or is fluidly connected to the at least one external central tube panel.
5. The solar receiver of claim 1, further comprising a second stiffener structure running from the first side edge to the second side edge across the first face and the second face of the wing tube panel at a second support elevation.
6. The solar receiver of claim 5, wherein the first support elevation and the second support elevation are not located at a middle section of the wing tube panel.
7. The solar receiver of claim 1, wherein the central receiver assembly further comprises an upper heat shield located above the at least one external central tube panel and a lower heat shield located below the central tube panel; wherein the wing assembly further comprises a heat shield having an upper face located above the wing tube panel, a lower face located below the wing tube panel, and a side face located distal from the central receiver assembly.
8. The solar receiver of claim 7, wherein an open space is present between the side face of the wing assembly heat shield and a side edge of the wing tube panel.
9. The solar receiver of claim 7, further comprising a horizontal heat shield located above the at least one external central tube panel. 6355800_3.docx
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201161560631P | 2011-11-16 | 2011-11-16 | |
US61/560,631 | 2011-11-16 | ||
US13/678,320 | 2012-11-15 | ||
US13/678,320 US9127857B2 (en) | 2011-11-16 | 2012-11-15 | High efficiency solar receiver |
PCT/US2012/065328 WO2013074821A1 (en) | 2011-11-16 | 2012-11-15 | High efficiency solar receiver |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ624443A NZ624443A (en) | 2016-07-29 |
NZ624443B2 true NZ624443B2 (en) | 2016-11-01 |
Family
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