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
  • F24S40/00—Safety or protection arrangements of solar heat collectors; Preventing malfunction of solar heat collectors
  • F24S40/50—Preventing overheating or overpressure
  • F24S40/52—Preventing overheating or overpressure by modifying the heat collection, e.g. by defocusing or by changing the position of heat-receiving elements
• • 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
  • F24S80/30—Arrangements for connecting the fluid circuits of solar collectors with each other or with other components, e.g. pipe connections; Fluid distributing means, e.g. headers
• • 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
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F11/00—Arrangements for sealing leaky tubes and conduits
• • 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

Definitions

• 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.
• Concentrated Solar Tower technology also known as Concentrating Solar Power (CSP) technology to harness the sun's energy to produce "green” electricity.
• CSP Concentrating Solar Power
• 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.
• 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.
• HTF heat transfer fluid
• 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.
• 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.).
• 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.
• U.S. Patent Application Serial No. 12/605,241 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.
• FIG. 1 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.
• 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.
• the present disclosure relates, in various embodiments, to heat absorbing tube panels and solar receivers incorporating such panels that are exposed to solar energy on two opposite faces.
• heat absorption on two faces can reduce the temperature differential between the hot face and the cold face and therefore provide more uniform tube temperature around the circumference of the tube. This results in significantly reduced thermal stresses in the tube and lower potential for tube failures. With lower tube stresses, the risk of failure due to stress corrosion is also reduced.
• the available heat absorbing area is doubled compared to a single side heated panel. The combination of reduced stresses and doubled absorbing area results in a panel that can accept more than twice as much solar energy, significantly increasing the efficiency of the panel.
• the solar receivers comprise an arrangement of heat transfer surfaces, a heat transfer fluid system structurally and functionally interconnected thereto, a vertical support structure, and a stiffener structure.
• a dual-exposure heat absorption panel comprising a tube panel and a structural support frame.
• the tube panel comprises a plurality of vertical tubes for conveying a heat transfer fluid.
• the tubes are interconnected by at least one upper header and at least one lower header.
• the tube panel has a first exposed face, an opposite second exposed face, an upper edge, a lower edge, a first side edge, and a second side edge.
• the structural support frame runs along the upper edge, the first side edge, and the second side edge of the tube panel.
• At least one tube in the tube panel is connected to the at least one upper header or the at least one lower header by a repair coupling surrounding the at least one tube and a prior header tube stub.
• the repair coupling may be located behind heat shields mounted to the structural support frame so that the repair coupling is not exposed to direct sunlight.
• the dual-exposure panel may further comprise a first stiffener structure running from the first side edge to the second side edge across the first exposed face and the second exposed face of the tube panel at a first support elevation.
• the stiffener structure is formed from a first support assembly and a second support assembly, each support assembly including: a support tube; a horizontal flange extending from the support tube and having a slot therein; and a scallop bar engaging one or more vertical tubes of 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 tube panel, and in some embodiments is larger.
• the dual-exposure panel may further comprise a second stiffener structure running from the first side edge to the second side edge across the first exposed face and the second exposed face of the tube panel at a second support elevation.
• the first support elevation and the second support elevation are not located at a middle section of the tube panel.
• a dual-exposure heat absorption panel comprising a tube panel and a structural support frame.
• the tube panel comprises a plurality of vertical tubes for conveying a heat transfer fluid.
• the tubes are interconnected by at least one upper header and at least one lower header.
• the tube panel has a first exposed face, an opposite second exposed face, an upper edge, a lower edge, a first side edge, and a second side edge.
• the structural support frame runs along the upper edge, the first side edge, and the second side edge of the tube panel.
• the tube panel includes at least one tube joined to a header tube stub on either the at least one upper header or the at least one lower header, an exterior diameter of the header tube stub being greater than a central exterior diameter of the at least one tube.
• an interior diameter of the at least one tube is the same as an interior diameter of the header tube stub.
• a dual-exposure heat absorption panel comprising a tube panel and a structural support frame.
• the tube panel comprises a plurality of vertical tubes for conveying a heat transfer fluid.
• the tubes are interconnected by at least one upper header and at least one lower header.
• the tube panel has a first exposed face, an opposite second exposed face, an upper edge, a lower edge, a first side edge, and a second side edge.
• the structural support frame runs along the upper edge, the first side edge, and the second side edge of the tube panel.
• the structural support frame includes a first heat shield framing the first exposed face of the tube panel, an open space being present between the first heat shield and the tube panel.
• a dual-exposure heat absorption panel comprising a tube panel, a structural support frame, a curtain, and means for guiding the curtain.
• the tube panel comprises a plurality of vertical tubes for conveying a heat transfer fluid.
• the tubes are interconnected by at least one upper header and at least one lower header.
• the tube panel has a first exposed face, an opposite second exposed face, an upper edge, a lower edge, a first side edge, and a second side edge.
• the structural support frame runs along the upper edge, the first side edge, and the second side edge of the tube panel.
• the structural support frame includes a first heat shield framing the first exposed face of the tube panel, the first heat shield including an upper face, a first side face, and a second side face.
• the curtain is located on the upper face of the first heat shield above the tube panel.
• the means for guiding the curtain is located on the first side face and the second side face of the heat shield.
• the curtain may have a length sufficient to cover the entirety of the tube panel.
• the means for guiding can include rails or cables. Sometimes, a bottom edge of the curtain includes weights.
• FIG. 1 is a plan (i.e. top) view of a conventional solar receiver design having a square orientation, with each tube panel having one exterior exposed face and one interior non-exposed face.
• FIG. 1A is a side cross-sectional view of a conventional tube panel with a light barrier and insulation.
• FIG. 1 B is a perspective view of the panel of FIG. 1 A.
• FIG. 2 is a first front view of a solar receiver of the present disclosure using a dual-exposure heat absorption panel having a limited number of tube passes.
• heat shields and panel stiffener support structures are removed to provide an interior view.
• FIG. 3 is a second front view of a solar receiver of the present disclosure using a dual-exposure heat absorption panel.
• panel stiffener support structures are visible, and heat shields are removed to provide another interior view.
• FIG. 4 is an exterior front view of a solar receiver of the present disclosure using a dual-exposure heat absorption panel. Here, the heat shields are in place.
• FIG. 5 is an exterior side view of a solar receiver of the present disclosure.
• FIG. 6 is a plan view showing a tube panel and a stiffener structure for the tube panel of the present disclosure.
• FIG. 7 is a side cross-sectional view of a tube panel and a stiffener structure for the tube panel as depicted in FIG. 6.
• FIG. 8 is a front view of the tube panel and stiffener structure as depicted in FIG. 6.
• FIG. 8A is a perspective view of the tube panel and stiffener structure as depicted in FIG. 6.
• FIG. 9 is an enlarged front view of a tube panel without stiffener structure showing the tube panel having multiple tube passes, upper headers, and lower headers.
• FIG. 10 is a schematic showing fluid flow through the dual-exposure heat absorption panel.
• FIG. 11 is a side cross-sectional view of the upper header and the tube panel, showing a possible repair coupling arrangement between an original tube and a replacement tube.
• FIG. 12 is a side cross-sectional view of the lower header and the tube panel, showing a tube stiffening arrangement.
• FIG. 13 is a front view of an alternative arrangement of the heat absorption panel, wherein an open space is located between the heat shield and the tube panel.
• FIG. 14 is a front view of the heat absorption panel showing a curtain arrangement by which the tube panel can be quickly covered.
• FIG. 15 is a side view of the heat absorption panel of FIG. 14.
• FIG. 16 is a front view depicting the lowering of a curtain to cover the tube panel of FIG. 14.
• the present disclosure relates to a dual-exposure or two-sided heat absorption panel and to solar receivers incorporating one or more two-sided heat absorption panels.
• the panels are designed to accept heat on two opposite sides or faces, rather than on only one side or face. This can reduce tube failures due to fatigue or stress corrosion, and for a given panel size the available heat absorbing area is doubled compared to a single side heated panel.
• the panels may include one or more stiffener structures or heat shields.
• 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.
• 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.
• applicable seismic loads and design codes are also considered.
• molten salt is used as the heat transfer fluid (HTF) that is run through the absorption panel.
• HTF heat transfer fluid
• molten salt solidifies at approximately 430°F (221 °C, 494°K).
• the molten salt can quickly cool and form plugs. Plugged tubes can cause delays at start up and could lead to tube failures.
• 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.
• FIG. 1A is a side view of a conventional tube panel 12 which utilizes one sided heat absorption
• FIG. 1 B is an enlarged perspective exploded view of the tube panel.
• This one-sided heat absorbing tube panel is used in the conventional solar receiver of FIG. 1.
• a reflective modular panel light barrier 36 is located behind the tubes 13 (i.e. the non-exposed face of the tube panel) opposite the heat absorbing (i.e. exterior) side of the tube panel.
• the light barrier 36 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 a tube attachment structure, such as a buckstay support system 20.
• the light barrier i.e. further interior of the solar receiver
• the light barrier is designed to protect the insulation 38, support structure 20, 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.
• FIGS. 2-4 are various front views of a solar receiver design with 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.
• 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 FIG. 5) 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.
• the tubes in the tube panel are interconnected by at least one upper header and at least one lower header.
• 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 along the upper edge 212, the first side edge 216, and the second side edge 218 of the tube panel.
• the structural support frame 300 includes a first vertical column 310, a second vertical column 320, and an upper horizontal beam 330 extending from an upper end 312 of the first vertical column to an upper end 322 of the second vertical column.
• the first vertical column 310 is adjacent the first side edge 216
• the second vertical column 320 is adjacent the second side edge 218, and the upper horizontal beam 330 is adjacent the upper edge 212 of the absorption panel.
• the tube panel 210 is connected to the structural support frame 300 through the upper header 242.
• the 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.
• the structural support frame 300 rests upon a base platform 204, which may be considered as providing a platform for the absorption panel.
• the base platform 204 is attached to or located upon a tower 206.
• a 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.
• the 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.
• 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.
• 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.
• 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.
• support tube 400 is visible on this first face.
• the support tube 406 provides stiffener structures on the second face.
• the number of stiffener structures can depend on the maximum unsupported length of the tube panel that will resist wind and seismic loads.
• the 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 tube panel into equal sections along its height.
• the first stiffener structure 401 is shown in the upper section 230
• the second stiffener structure 402 is shown in the lower section 234.
• 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.
• 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 tube panel.
• some heat transfer fluid such as oil or water
• 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.
• FIG. 4 the structural support frame (not visible; see FIG. 2) 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 FIG. 4, but is visible in FIG. 2.
• a first heat shield 340 frames the first face 222 of the tube panel 210.
• a second heat shield 360 also frames the second face 224 of the tube panel.
• the heat shield 340 includes an interior edge 342 that forms a window in the heat shield through which the tube panel 210 is visible. Dotted lines show the outline of the 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 tube panel, but could also be arranged with a gap between the heat shield and side edges of the tube panel to reduce 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.
• FIG. 5 is an exterior side view of the solar receiver design.
• 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 is shown here as being wider than the apex 304 of the structural support frame; this provides additional stability.
• a heat shield 370 is also present on the sides of the structural support frame 300.
• FIGS. 6-8A are different views of one exemplary embodiment of a stiffener structure.
• FIG. 6 is a plan (i.e. top) view of the exemplary embodiment.
• FIG. 7 is a side cross-sectional view of the exemplary embodiment.
• FIG. 8 is a front view of the exemplary embodiment.
• FIG. 8A is a perspective view.
• 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.
• first support assembly 410 is part of the support tube 400
• 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.
• 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.
• 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.
• scallop bar 440 is shown 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 FIG. 3). 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 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 tube panel. (Note the axis of the support tube is perpendicular to the axis of the tubes in the 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.
• 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.
• 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.
• the support tubes 400, 406 that make up the 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.
• the support tubes use a different cooling fluid. This could be accomplished, for example, by connecting the support tubes to separate headers.
• 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.
• 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.
• each support tube connects to the upper header and the lower header on the same side of the tube panel.
• 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.
• FIG. 9 is an enlarged front view of the tube panel, with the stiffener structure removed.
• the tube panel 500 includes a plurality of tube passes 510, depicted here with four tube passes.
• Each tube pass comprises one or more tubes 512 which are parallel to each other.
• the tubes 512 pass between an inlet header 514 and an outlet header 516 to form a body or wall 537 upon which the focused solar energy from the heliostats can be directed.
• the tube passes 510 are interconnected using jumper pipes 502.
• the tube passes 510 are organized in a vertical or axial direction, such that the heat transfer fluid flows in an alternating up-down direction through the tube passes, which is indicated with arrows 505. This change in flow direction is referred to herein as a serpentine flow path.
• the flow path begins at inlet 504 and ends at outlet 506. It should be noted that if there is an even number of tube passes 510, the inlet 504 and the outlet 506 may be located along a common edge 508 or 544 of the tube panel 500. Alternatively, the inlet 504 and outlet 506 can be located on opposite edges 508 and 544 of the tube panel 500 when an odd number of tube passes is used. In other words, the inlet and the outlet can be independently located at the top edge 544 or the bottom edge 508, as required by the design of the receiver. As depicted here, the inlet 504 and the outlet 506 are both located along the top edge 544.
• An inlet header is defined as such relative to the direction of flow.
• header 531 is considered the inlet header and header 532 is considered the outlet header.
• header 542 is considered the inlet header and header 541 is considered the outlet header.
• the headers of the tube passes can also be designated as upper headers 531 , 541 , 551 , 561 and lower headers 532, 542, 552, 562 wherein the upper headers are located above the lower headers.
• one set of headers 532, 542, 552, 562 is located in lower plane 508, and the other set of headers 531 , 541 , 551 , 561 is located in an upper plane 544.
• the tubes 536 form a body 537.
• the tubes are closely spaced and parallel to each other.
• the upper header 531 has a width 533
• the lower header 532 has a width 534.
• the body 537 can have a width 538 that is greater than the header widths 533, 534.
• the body 537 may be wider than the lower header 532 and the upper header 531.
• the width is measured in the horizontal direction.
• the lower header and the upper header of each tube panel are the same width.
• the ratio of the body width 537 to the width of the lower header or upper header 532, 531 can at least 1 .01 :1 , and may range from 1 .01 to 1 .5. This permits the spacing between edge tubes in adjacent panels to be the same as the close spacing between tubes within a panel.
• the upper headers of adjacent tube panels would be laterally separated from each other.
• the lower headers of adjacent tube panels would also be laterally separated from each other. This may allow the tube panels to expand differentially with respect to each other because they are operating at different temperatures.
• FIG. 10 is a schematic diagram illustrating fluid flow through the dual- exposure heat absorption panel 600.
• a riser 670 provides cold fluid to an inlet vessel 660 from cold storage tank 652.
• "cold" molten salt may be pumped from the cold storage tank having a temperature of about 550°F.
• An inlet pipe 672 fluidly connects the inlet vessel 660 to the tube panel inlet 674.
• the jumper pipes 696 between tube passes is also illustrated.
• An outlet pipe 678 fluidly connects the tube panel outlet 676 to an outlet vessel 662.
• the heat transfer fluid (HTF) can flow from the inlet vessel 660 through the tube panel 684 to the outlet vessel 662.
• a downcomer pipe 688 leads from the outlet vessel 662 back down to grade, where the "hot" fluid can flow into hot storage tank 650.
• the inlet vessel 660 is optional and not required, which is indicated by the use of dotted lines, for example if the heat transfer fluid is steam/water.
• the outlet pipe 678 and outlet vessel 662 are also optional and not required, which is indicated by dotted line. Without an outlet vessel, the HTF flows from the tube panel outlet 676 directly to the downcomer pipe 688 via outlet pipe 691.
• a bypass line 690 also connects the riser 670 to the downcomer pipe 688. If desired, this bypass flow path can prevent the HTF from flowing through the tube panel 684.
• 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 650 through the shell side of a heat exchanger 654. Water enters the tube side of heat exchanger 654 and is converted to steam. The steam can be sent to turbine 656, which drives an electrical generator 658. The cooler HTF leaving the heat exchanger then returns to the cold storage tank 652, where it is pumped to the receivers to repeat the energy collection process described above.
• 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.
• the solar receiver can include a vent valve 692 for each independent flow path which are both vented through the top of the downcomer pipe 688.
• the vent valve is typically located near the top of the downcomer pipe 688, and the vent piping 694 is also illustrated connecting the flow path to the downcomer pipe.
• One drain valve 697 is typically provided for each pair of tube passes, and is located beneath the tube passes.
• the drain piping 698 is also illustrated, and connects to the downcomer 688 so that fluid present in the tube panel drains and flows into the downcomer pipe 688.
• the vent valves and drain valves are automated.
• FIG. 11 This repair coupling is significantly easier to weld when replacing a failed tube.
• the header 750 is shown here, with a header tube stub 760 from the prior (failed) tube extending from the header.
• the prior header tube stub ends at a line 762, which can be cut in the field depending on the failure location of the original tube.
• the prior tube stub is a portion of the former existing tube that did not fail.
• the new replacement tube 780 is abutted to the field-cut line 762.
• a repair coupling 770 is used to surround the ends of the tube stub and the replacement tube, similar to inserting the two tubes into a cylindrical sleeve. Field welds can then be used to join the repair coupling 770 to the tube stub 760 and the replacement tube 780 respectively (e.g. using a fillet weld).
• This repair coupling 770 is located behind a heat shield, and is not exposed to the sunlight from the heliostats.
• the tube panel can be stiffened using different means, such as the stiffener structure seen in FIGS. 6-8. Another stiffening structure can be located in the heat-shield protected sections of the absorption panel. This is shown in FIG. 12.
• the lower header 250 is depicted here as having a header tube stub 720.
• the header tube stub has an exterior diameter 722 and an interior diameter 724.
• a wall tube 700 in the tube panel is also illustrated.
• the tube has an exterior diameter 712 and an interior diameter 714.
• the interior diameter 724 of the tube stub 720 is the same as the interior diameter 714 of the tube 710. However, the exterior diameter 722 of the tube stub is larger than the exterior diameter 712 of the tube.
• the wall of the tube stub 720 has a thickness 707 that is greater than the thickness 705 of the wall of the tube 710.
• the tube stub 720 and the tube 710 are welded together using a fillet weld. Put another way, there is a discontinuous change in thickness.
• the heavier and thicker wall tube would increase the rigidity of the tube panel between the upper header and the lower header, permitting longer light exposed sections for the tube panel. Additionally, any support clips or welds could be larger and stronger due to the thicker tubes.
• FIG. 13 presents an alternative heat shield design.
• the interior edge 342 of the heat shield 340 abuts the side edges 216, 218 of the tube panel.
• a gap or an open space 201 is present between the side edges 216, 218 of the tube panel and the interior edge 342 of the heat shield.
• Such an open space creates a free-standing tube panel.
• This arrangement allows the heliostats to be focused more uniformly across the width of the tube panel, which generally requires some heliostats to be focused towards the edges of the tube panel.
• the open space provides a buffer that reduces spillage of concentrated sunlight upon the heat shields. Instead, the concentrated sunlight can pass through the open space, though it would be considered an energy loss.
• the interior edge 342 of the heat shield includes an upper edge 344, a lower edge 346, a first side edge 348, and a second side edge 350.
• An open space 201 is present between the interior side edges 216, 218 of the heat shield and the side edges 348, 350 of the tube panel.
• the open space has a width of at least 1 % of the width of the tube panel. Support tubes 400 and 406 are also visible here.
• HTF heat transfer fluid
• inlet and outlet HTF vessels were used as buffers.
• the inlet vessel was pressurized with compressed air at a pressure high enough to continue flowing HTF contained within the inlet vessel through the tube panels long enough to allow the heliostats to be defocused off of the receiver.
• FIG. 14 and FIG. 15 depict another arrangement which is permitted with the solar receiver designs of the present disclosure.
• the heat shield 340 includes an upper face 352, a first side face 354, and a second side face 356. Again, a window or aperture 355 is present within the heat shield through which the tube panel 210 is visible.
• a curtain 750 is located on the exterior of the upper face 352 of the first heat shield above the tube panel 210. Here, the curtain is rolled up in a stowed position.
• the curtain can be made from a high temperature resistant material, such as a ceramic blanket.
• Means 752 for guiding the curtain are located on the first side face 354 and the second side face 356 of the heat shield. As seen in FIG. 15, a curtain can also be located on the second side on the second heat shield 360. Support tubes 400 and 406 are also visible in FIG. 14.
• the curtain When a trip condition exists, the curtain would be released and fall in front of the tube panel to block the concentrated sunlight coming from the heliostats. This would protect the tube panel from overheating until the heliostats could be defocused off of the receiver, eliminating the need for an inlet vessel.
• One benefit of this solar receiver design is that the edges of the curtain can be positively guided to pull the curtain down and keep the curtain from blowing in the wind, which could uncover portions of the tube panel.
• the curtain can extend beyond the width of the tube panel.
• the edges of the curtain can be guided, for example via rails (like a garage door) or using guide cables.
• the guidance means is shown as a path 758 through the heat shield, with cables attached to the curtain. This also protects the mechanism for driving the curtain down over the tube panel.
• the bottom edge of the curtain may be weighted.
• cables could be used to pull the curtain down from the sides.
• FIG. 16 is a front view illustrating the lowering of the curtain.
• the curtain 750 is illustrated as being lowered about halfway down.
• the bottom edge of the curtain is weighted (reference numeral 754).
• Guide cables 756 are running down the cable paths 758, and are attached to the bottom corners of the curtain.

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• 2012
  • 2012-11-15 EP EP12850357.0A patent/EP2780644A4/de not_active Withdrawn
  • 2012-11-15 CN CN201280056209.9A patent/CN103946643A/zh active Pending
  • 2012-11-15 IN IN3666CHN2014 patent/IN2014CN03666A/en unknown
  • 2012-11-15 MX MX2014005494A patent/MX2014005494A/es not_active Application Discontinuation
  • 2012-11-15 AU AU2012340374A patent/AU2012340374A1/en not_active Abandoned
  • 2012-11-15 BR BR112014011785A patent/BR112014011785A2/pt not_active IP Right Cessation
  • 2012-11-15 WO PCT/US2012/065324 patent/WO2013074818A1/en active Application Filing
  • 2012-11-15 US US13/677,519 patent/US20130118480A1/en not_active Abandoned
  • 2012-11-15 CA CA2855388A patent/CA2855388A1/en not_active Abandoned
• 2014
  • 2014-04-22 IL IL232164A patent/IL232164A0/en unknown
  • 2014-04-24 ZA ZA2014/03010A patent/ZA201403010B/en unknown
  • 2014-05-15 MA MA37039A patent/MA35650B1/fr unknown

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