Tight structure for external solar receiver in a tower of a concentrating solar power plant

Abstract

An external solar receiver, for a concentrating thermodynamic solar power plant of the type with a tower and heliostat field, has a wind tight modular inner structure, also called casing, and a plurality of heat exchanger tube receiver panels fastened to that inner structure. Each panel has a plurality of metal boxes supporting the heat exchanger tubes and assembled to one another by assembly means allowing the disassembly, each box being covered with thermal insulation via an anchor. The tubes are secured to the boxes by a removable and floating connector.

Claims

1. An external solar receiver for a concentrating thermodynamic solar power plant of the type with a tower and heliostat field, the tower comprising: a wind tight modular inner structure, as a casing; and a plurality of heat exchanger tube receiver panels fastened to that inner structure, wherein each panel includes a plurality of metal boxes supporting the heat exchanger tubes, the plurality of metal boxes being removably fastened together by one or more removable fastening devices, wherein each metal box is covered with thermal insulation via an anchor, wherein the heat exchanger tubes are secured to the boxes by a removable and floating connector, allowing thermal expansion of the heat exchanger tubes and thermal expansion of a part of their support subject to a high temperature both in a longitudinal direction of the heat exchanger tubes and in transverse directions thereto, wherein each heat exchanger tube includes several welded eyelets distributed over a height of the heat exchanger tube, each of the several welded eyelets being configured to slide along a respective key under axial thermal expansion of the heat exchanger tube, and wherein each respective key is fastened to the metal box through the thermal insulation by support bars, so that movement of the heat exchanger tubes under expansion, substantially in the longitudinal direction and along a plane of the panel, occurs outside the thermal insulation, the solar receiver further comprising: different boxes including the thermal insulation, assembled with slight play facilitating their disassembly; and a removable seal provided between the different boxes to ensure wind tightness, wherein the removable seal includes a seal mounted crushed by bolting between flanges formed by U-shaped ends of two adjacent boxes and by a companion flange or an H-shaped profile.

2. The solar receiver of claim 1, wherein each metal box comprises a single piece rectangular metal sheet bent in a U shape on each side of the metal box, and wherein corners of each box are welded.

3. The solar receiver of claim 1, wherein the thermal insulation is a block with a rectangular section corresponding to that of the metal boxes and including, on each of its sides, a male or female baffle, so as to be able to be assembled with an adjacent insulation block including additional baffles on its sides.

4. The solar receiver of claim 1, further comprising: a slightly bent staple configured to be mounted on two adjacent keys so as to ensure the locking of the keys.

5. The solar receiver of claim 1, wherein the eyelets welded on the heat exchanger tube include a saddle-shaped base.

6. The solar receiver of claim 1, wherein the heat exchanger tubes are connected to one another via their corresponding keys by lateral intermediate support plates providing a junction between the bars and the tubes.

7. The solar receiver of claim 6, wherein the bars are connected to the support plates using axes that are inserted into oblong holes of the support plates.

8. An external solar receiver for a concentrating thermodynamic solar power plant of the type with a tower and heliostat field, the tower comprising: a wind tight modular inner structure, as a casing; and a plurality of heat exchanger tube receiver panels fastened to that inner structure, wherein each panel includes a plurality of metal boxes supporting the heat exchanger tubes, the plurality of metal boxes being removably fastened together by one or more removable fastening devices, wherein each metal box is covered with thermal insulation via an anchor, wherein the heat exchanger tubes are secured to the boxes by a removable and floating connector, allowing thermal expansion of the heat exchanger tubes and thermal expansion of a part of their support subject to a high temperature both in a longitudinal direction of the heat exchanger tubes and in transverse directions thereto, wherein each heat exchanger tube includes several welded eyelets distributed over a height of the heat exchanger tube, each of the several welded eyelets being configured to slide along a respective key under axial thermal expansion of the heat exchanger tube, and wherein each respective key is fastened to the metal box through the thermal insulation by support bars, so that movement of the heat exchanger tubes under expansion, substantially in the longitudinal direction and along a plane of the panel, occurs outside the thermal insulation, the solar receiver further comprising a slightly bent staple configured to be mounted on two adjacent keys so as to ensure the locking of the keys.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. All features described and/or illustrated herein can be used alone or combined in different combinations in embodiments of the invention. The features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:

(2) FIG. 1 a diagrammatic sectional view of an individual box making up the modular casing according to the present invention;

(3) FIG. 2 a diagrammatic sectional view of several boxes (three in the case at hand) according to claim 1, assembled to one another with slight play and connecting means between the boxes ensuring wind tightness;

(4) FIG. 3 a diagrammatic sectional view of several embodiments of the box according to FIG. 1 with a male or female baffling of the thermal insulation anchored on the metal sheet, on either side (in the drawing: top side and bottom side);

(5) FIG. 4 an elevation view of the device for fastening an individual tube to a box, comprising bars and a key, as well as an eyelet welded on the tube, according to one embodiment of the present invention;

(6) FIG. 5 a detailed view of the key of FIG. 4 with a first solution for locking the key at the bars;

(7) FIG. 6 a detailed view of the key of FIG. 4 with a second solution for locking the key at the bars;

(8) FIG. 7 a planar view of one particular embodiment of the eyelet welded on the tube according to FIG. 4;

(9) FIG. 8 a perspective view of the assembly of a solar receiving panel comprising several modular boxes according to the invention, seen from behind, i.e., from the cold side; and

(10) FIG. 9 a detailed view of the mechanical support system for the solar tubes, according to the invention, ensuring its maintenance and guidance and reacting wind forces.

DETAILED DESCRIPTION

(11) An aspect of the present invention provides a solution for the design of a casing of an external solar tower receiver so that the latter can perform the following functions: wind tightness and an effective thermal barrier, insulation between the tube side, which is very hot, and the inner tower side, which must be kept at an acceptable temperature for staff and special equipment, and maximum reduction of heat losses so as not to damage the performance.

(12) The casing preferably also allow wind or earthquake forces exerted on the solar tube panels and the wall of the casing itself to be reacted.

(13) The casing preferably also be designed for an assembly of the tubes facilitating their maintenance or replacement.

(14) Lastly, the casing preferably allow vertical and horizontal expansions of the two panels and be designed to avoid mechanical movements of support elements through the insulation.

(15) An aspect of the present invention provides an external solar receiver for a concentrating thermodynamic solar power plant of the type with a tower and heliostat field, said tower comprising a wind tight modular inner structure, also called casing, and a plurality of heat exchanger tube receiver panels fastened to that inner structure, each panel comprising a plurality of metal boxes supporting the heat exchanger tubes and assembled to one another by assembly means allowing the disassembly, each box being covered with thermal insulation via an anchoring means, the tubes being secured to the boxes by a removable and floating connecting means, i.e., allowing the thermal expansion of the tubes and of the part of their support subject to the high temperature both in the longitudinal direction of the tubes and in the transverse directions thereto, characterized in that each tube is provided with several welded eyelets, distributed over the height of the tube, able, under the effect of the axial thermal expansion of the tube, to slide in a key, which in turn is fastened to the box through the thermal insulation by support bars, so that the movement of the tubes under the effect of the expansion, essentially in the longitudinal direction and along the plane of the panel, is done outside the thermal insulation. Thus, it is the support structure that allows the expansion of the receiver panel without any movement through or in the insulation.

(16) According to preferred embodiments of the invention, the solar receiver further comprises at least one of the following features, or any suitable combination thereof: the metal boxes are in a single piece and made up of a rectangular metal sheet bent in a U shape on each of its sides, the corners of each box being welded; the thermal insulation is a block with a rectangular section corresponding to that of the boxes and including, on each of its sides, a male or female baffle so as to be able to be assembled with an adjacent insulation block including additional baffles on its sides; different boxes with the thermal insulation are assembled with slight play facilitating their disassembly, a removable sealing means being provided between the boxes to ensure wind tightness; the removable sealing means includes a seal mounted crushed by bolting on the one hand between the flanges formed by the U-shaped ends of two adjacent boxes and on the other hand a companion flange or an H-shaped profile; the key is provided with two diametrically opposite lugs able to cooperate with two hollows formed in each bar, so as to be able to lock the key by rotation by a quarter revolution, a thin bent metal sheet being provided to prevent rotation of the key around itself; a slightly bent staple able to be mounted on two adjacent keys is provided to ensure the locking of said keys; the eyelets welded on the tube have a saddle-shaped base; the tubes are connected to one another via their corresponding keys by lateral intermediate support plates that provide the junction between the bars and the tubes; the bars are connected to the support plates using axes that are inserted into oblong holes of the bars.

(17) A specific technical solution provided by the present invention lies not only in the requested functions for the purposes of the invention, but also in a configuration that can easily be disassembled from the rear, i.e., from the inside of the tower, accessible to maintenance staff, through modular elements easy for the assembly staff to manipulate. This results in easy access to the rear of the tubes, and therefore the possibility of an inspection and maintenance of the tubes, which are the most stressed part of the solar receiver.

(18) FIG. 1 shows a box 1 of the modular casing subdivided into a plurality of boxes 1 with a preferred size of approximately 1 to 2 m.sup.2. Each box 1 is made up of a metal sheet 2 bent into a U shape 3 on each of its four sides. The corners of each box are welded, forming a rigid assembly.

(19) A specific thermal insulation 4 is anchored on the metal sheet 2, on the high-temperature side, using an anchoring system 5 known by those skilled in the art. Baffles 6 are arranged in the insulation 4 so as to provide a thermal barrier between the adjacent boxes 1, while avoiding solar radiation leaks through the panels. Depending on the location of the box 1 in the assembly of the solar receiver, the baffling 6 will be male and/or female on either side, as shown in FIG. 3.

(20) As shown in FIG. 2, the boxes 1 are then assembled to one another with slight play 7 and the wind tightness is provided either by a seal 8 and a companion flange 9, or by a seal 8 and an H-shaped profile 10. In the latter case, the H-shaped profile 10 will react the wind and earthquake loads and retransmit those forces to the main framework (as for example shown in FIG. 8). The companion flange 9 or the H-shaped profile 10 are assembled by a removable assembly means, preferably assembled using bolts 11, on corresponding pre-pierced flanges of the box, by crushing the sealing gasket 8. The assembly play 7 between the boxes further allows easy disassembly.

(21) As shown in FIG. 4, the transmission of the wind and earthquake forces acting on the tubes 20 toward the sheet metal 2 of the casing 1 and the H-shaped profiles 10 is done by an eyelet 21 welded on the tube 20 and sliding along a key 12, allowing the axial thermal expansion of the tube 20, but limiting its lateral movements. All of the tubes 20 are supported individually.

(22) As also shown in FIG. 4, each key 12 is maintained at the casing 1, 2 by two bars 13 preferably made in the form of flat sections. Owing to two lugs 14 arranged on the key 12, and two hollows arranged in the bar 13, the key 12 will be kept in place, even in case of vertical force oriented upward, rotating the latter by a quarter revolution. A thin bent metal sheet 15 will prevent the rotation of the key 12 so that the lugs do not find themselves across from the assembly hollows (see FIG. 5). Other details of the connection are shown in FIG. 9 (see below).

(23) As shown in FIG. 6, another locking solution of the key 12 consists of using a staple 17 mounted on two consecutive or adjacent keys 12 slightly bent so as to keep it in place.

(24) As shown in FIG. 7, the eyelet 11 welded on the tube 20 will also advantageously have a particular shape with a saddle-shaped base 18, allowing easy welding on the tube while better distributing the forces on the tube, thus minimizing stresses.

(25) FIG. 8 shows a realistic embodiment for the assembly of the casing of a panel 25 seen from behind, and in particular with two horizontal series of boxes 1 assembled with horizontal H-shaped profiles 10 for wind tightness and beams 19 that react wind forces. FIG. 8 also shows a corner box 23. Like the panels, the corner box 23 is bolted on the wind beams 19. The thermal insulation is not shown.

(26) As shown in FIGS. 4 and 9, the flat portions 13 themselves are retained by the casing 1, 2 by forming a floating assembly, which allows the flat portions 13 to expand over their lengths, the latter also being subject to a high temperature on the outer side. FIG. 9 also shows that all of the tubes 20 and therefore the associated keys 12 are advantageously laterally connected by metal support plates 16 that serve as a junction between the tubes 20 and the support flats 13. Also advantageously, two flat portions 13 are connected to support plates 16 using axes 26 that are inserted into oblong holes 27 of the flat portions 13, which allows the horizontal expansion of the panels 25.

(27) According to an aspect of the invention, the tube panels can move vertically, but also horizontally under the effect of the thermal expansion. Thus, the support plates 16 make it possible to react the horizontal expansion of the tubes, by expanding with the tubes, since those plates 16 are also subjected to high temperatures. Furthermore, the connections by rods and oblong holes of the flat portions 13 and the support plates 16 also facilitate the horizontal expansion of the panels.

(28) The design of an aspect of the system allows an independent assembly of the tubes, which facilitates the maintenance and/or replacement. The saddle welding of the tubes to the eyelets makes it possible to distribute the forces on the tube, preferably with a thickness of the edge of the saddle in the same order of magnitude as the thickness of the tube.

(29) Another advantage of an aspect of the invention is that this expansion of the tubes and their direct support structure, and the resulting movement, is done in large part outside the installation (unlike the connecting rod system described in WO 2010/048578, for example).

(30) Lastly, the different modular boxes can be coated with their insulation either in the plant, or on the assembly site. The boxes are sized to be able to be manipulated by two people, if applicable equipped with appropriate handling tools (maximum weight of approximately 150 kg).

(31) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.

(32) The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article a or the in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of or should be interpreted as being inclusive, such that the recitation of A or B is not exclusive of A and B, unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of at least one of A, B, and C should be interpreted as one or more of a group of elements consisting of A, B, and C, and should not be interpreted as requiring at least one of each of the listed elements A, B, and C, regardless of whether A, B, and C are related as categories or otherwise. Moreover, the recitation of A, B, and/or C or at least one of A, B, or C should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B, and C.

REFERENCE SYMBOLS

(33) 1. box

(34) 2. metal sheet

(35) 3. U-shaped bend of the metal sheet (flange)

(36) 4. thermal insulation

(37) 5. anchoring

(38) 6. baffle

(39) 7. play between adjacent boxes

(40) 8. seal

(41) 9. companion flange

(42) 10. H-shaped profile

(43) 11. bolt

(44) 12. removable key

(45) 13. support bar (flat)

(46) 14. lug

(47) 15. anti-rotation bent metal sheet

(48) 16. intermediate lateral plate

(49) 17. staple

(50) 18. saddle base

(51) 19. wind beam

(52) 20. exchanger tube

(53) 21. eyelet welded on tube

(54) 22. stiffener

(55) 23. corner box

(56) 24. movement of the tubes by expansion

(57) 25. exchanger tube panel

(58) 26. connecting axis

(59) 27. oblong hole