MX2013001634A

MX2013001634A - Solar receiver panel.

Info

Publication number: MX2013001634A
Application number: MX2013001634A
Authority: MX
Inventors: Jesus María Lata Pérez; Pedro Ángel Bayón Sanz
Original assignee: Sener Ing & Sist
Priority date: 2013-02-11
Filing date: 2013-02-11
Publication date: 2014-09-02
Also published as: MX341809B

Abstract

A solar receiver panel comprising a header comprising header body (18, 18') having a header wall surrounding an inner chamber (11, 11'), at least one access opening (21, 21') communicating with the inner chamber (11, 11') with a substantially spherical shape for connecting a fluid pipe, and a plurality of junction nozzles (16, 16') provided in the header wall which are connectable to respective solar absorption pipes (14) wherein at least one of the junction nozzles (16, 16') are located in a spherical segment of the inner chamber (11, 11') that is transversally opposed to said access opening (21, 21'), been the access opening (21, 21'), inner chamber (11, 11') and nozzles (16, 16') arranged to allow a thermal fluid to flow there through.

Description

SOLAR RECEIVER PANEL FIELD OF THE INVENTION The present invention relates to the technical field of solar absorption panels comprising collectors and, particularly, refers to solar absorption panels comprising collectors used to distribute and collect solar absorption tubes from a solar receiver panel, usually a solar collector of molten salt, although it can also be applied to absorption panels using other high temperature transmission fluids.

STATE OF THE ART A thin-walled cylindrical collector with constant cross-sections and a thin-walled collector with varying cross-sections in solar absorption panels receiving molten salt has been used, to which solar absorption tubes are connected by means of nozzle couplings that have been pre-machined and welded later. In some cases, the nozzles have been extruded directly from the manifold. Such embodiments have been disclosed in US-6736134-B2 and its equivalent O 03/021159 A2, and in US2009 / 250051 Al and its equivalent ES-2263394-B1 respectively.

Some of the constructions of this type subject the areas that join the collector body with the solar absorption tubes to high thermal stresses. These thermal stresses are caused by rapid temperature changes in the molten salts that flow through the collector due to the passage of clouds over the heliostat field of a solar plant. These thermal stresses due to sudden changes in temperature can be attenuated by placing linings or other thermal protection on the nozzles that join the solar absorption tubes, with the collector. However, these protections have geometries that are complex with respect to manufacturing and are difficult to assemble. Without this protection the operational life time of the plant is extremely short.

On the other hand, this collector requires a minimum step cross section to evenly distribute the flow of salts or other transmission fluid through all the solar absorption tubes connected to the collector, with the least possible pressure loss. However, it is well known that the flow of molten salt or transmission fluid is not uniform along the manifold and that such a variable flow distribution will depend on the arrangement of the connections in the manifold of the tube or tubes that feed it and the it must also absorb like a container that holds pressure in these parts that are far away from the manifold feed tubes, which implies that its main body requires wall thicknesses larger than desired, which in turn are again detrimental to the thermal stresses as they are directed towards the nozzles that connect the collector to the tubes. I In the design of collectors that have sections Transversal variables and thin walls, the goal is to provide an improved collector design that is suitable for use in solar receiver panels for molten salts or any other transmission fluid, more effectively supporting the thermal stresses experienced by the nozzles that connect the collector to the solar absorption tubes.

Therefore it is a main object of this collector design for use in solar panels of molten salt or other transmission fluid, which allows to use the same concept of a nozzle that connects the collector and di solar absorption pipe, for all pipes connected to it including those areas of high flow as of low flow of salts or other fluids, of the collector, thus achieving the resulting advantages with respect to manufacturing and costs.

DESCRIPTION OF THE INVENTION The present invention aims to comply with the objects mentioned above by means of an absorption panel comprising a collector.

The collector for the solar absorption panel according to the invention comprises a collector body having a collector wall surrounding an internal chamber, at least one access opening communicating with the internal chamber for connecting a fluid tube, and a plurality of connection nozzles provided on the wall of the manifold that can be connected to respective solar absorption tubes, the opening being of access, the internal chamber and the nozzles arranged to allow a thermal fluid to flow through them, characterized in that the internal chamber has a substantially spherical shape; at least one of the junction nozzles is located in a spherical segment of the internal chamber which is transversely opposite said access opening.

The term "thermal fluid" as used herein includes molten salts and other heat transfer fluids that are known in the art.

Preferably, the collector body of the panel also it has a substantially spherical shape, since typically the solar panels are connected in series and, therefore, generate significant pressures on their collectors to ensure that the fluid flows at the desired flow rate. These pressures, arising from said fact, and the tubes exposed to the outside, must be small to withstand the high thermal loads received and, therefore, require large wall thicknesses in the collector, which goes against the transient thermal stages. caused by clouds, for example, governed by the thermal differential inertia between the tubes (thin and with low mass) and the collector (heavy and with a lot of mass). In this sense, both the spherical geometry of the collector and the size as small as possible equal to or less than 1.5 times the sum of the sections of the internal passages of the absorption tubes I solar that are connected to the collector, compatible with unja holes in the collector wall, for example by welding. Preferably, the attachment nozzles are uniformly distributed in the collector wall. On the other hand, the at least one access opening can be an access nozzle formed by extrusion from the collector wall or, alternatively, an access nozzle fixed in an access hole in the collector wall.

From a theoretical point of view, a sphere is the optimum shape for a container that has to withstand internal pressure since a container with this shape can be made with a thinner wall than the containers that have other shapes. A spherical shape, therefore, leads to saving material, inspections and time in the manufacturing process. In addition, it allows to reduce substantially ° C, such as high mechanical strength, high resistance to stresses caused by temperature, adequate resistance to corrosion under pressure and high temperature compared to thermal fluids such as molten salt such as nitrate salts or other thermal transmission fluids, low coefficient of thermal expansion so that stresses originating from thermal deformations can be avoided, or at least minimized, weldability, formability and that is a common use material. High performance alloys based on Ni ('superalloys') such as INCONEL 625 or similar alloys are suitable candidates.

The union nozzles can be formed, for example by extrusion from the material of the spherical body or they can be separate elements made by way of example by pressing, extrusion or machining, which are inserted into holes made in the spherical body.

An important function of the collector is to provide a uniform distribution of the thermal fluid flows to the solar absorption tubes with the minimum possible pressure losses. To achieve this, it is advantageous that the sum of the sections of the internal passages of the solar absorption tubes be at least equal to the section of the internal passage of the solar absorption tube. intake pipe that feeds the thermal fluid to the manifold or, when more than one intake pipe is provided, to the sum of the sections of the internal passages of the intake pipes.

The maximum cross-section of the collector body, which is the maximum internal diameter of the sphere, must be the smallest possible cross-section that allows forming the union nozzles from the material of the collector body or, where appropriate, allowing to fit and weld the union nozzles on the collector body, but must be at least equal to 1.5 times the sum of the sections of the internal passages of connect to the collector. flow distribution, thanks to the geometry is of the pressures inside the collector and, therefore, to the uniformity of the flow to all the tubes that it connects, with all the advantages that it supposes, which does not happen in a cylindrical collector in which the diameter reduction is limited to obtain a distribution flow as evenly as possible between all connecting pipes, so that it is unable to further reduce its diameter The spherical collector according to this invention provides a series of advantages over a cylindrical collector conventional that has constant cross sections variables The spherical collector improves the uniformity of distribution of the thermal fluid flow through the solar absorption tubes connected to it, so as to reduce the thermal stresses generated with the appearance of transient changes in the union nozzles that connect the collector with the solar absorption tubes, so that the mechanical stresses due to pressure in the corresponding areas are reduced as a result of the reduction of the cross section of the step, since tension is caused with an otherwise equal pressure load. To its Again, this implies additional relevant advantages such as the possibility of using thinner collector walls.

I the collector body that allow the collector to better support the strong thermal stresses in the areas where the collector is attached to the intake or evacuation tube and to the connection nozzles to which the solar absorption tubes are connected, during the transient passage of clouds over the heliostat field of the solar plant in which the collector is used.

Another advantage of the collector of the present invention is It results in gradients of less temperature and therefore a lower thermal stress in the areas of the junction nozzles caused by the transient temperature changes e: the thermal fluid produced by the passage of clouds, so that the life time substantially increases operative The solar receiver panel comprises a first collector with an inlet for a thermal fluid, a second collector with an outlet for the thermal fluid, and a plurality of tubes. of solar absorption connected to said collectors, with at least one of the collectors, preferably both, being a collector as previously described.

BRIEF DESCRIPTION OF THE FIGURES Next in the present document, aspects of the invention will be described based on the drawings, in which Figure 1 is a schematic view partly in section of a solar absorption panel belonging to a central solar receiver provided with collectors according to an embodiment of the invention; Figure 2 is a side view of a manifold present in the panel shown in Figure 1; Figure 3 is a top plan view of the manifold shown in Figure 2; Figure 4 is a bottom plan view of the manifold shown in Figures 2 and 3; Figure 5 shows perspectives from above and descending below another embodiment of a spherical collector having a plurality of nozzles.

EMBODIMENTS OF THE INVENTION Figure 1 shows a solar absorption panel -12 constituted by a plurality of solar absorption tubes - 14- parallels whose respective ends are connected to hollow spherical main bodies -18, 18 of the collectors -10, 10'- by means of respective union nozzles -16, 16'-. Preferably, the ends of the tubes -14- are attached to the union nozzles -16, 16- by welding, and more preferably by butt welding. To a large extent, the reliability of the collector -10, 10 is, conditioned by said welds, for which s, prefer automated welding.

An inflow flow of molten salt or other transmission fluid enters the solar absorption panel -12- through of a first opening -21- for example a nozzle with entrance of the hollow spherical body -18- in which the flow is distributed by means of the nozzles -16- to the various tubes -14-. The flows thus divided pass through tubes I of absorption -14- towards the nozzles -16'- of the hollow spherical body -18'- of a second collector -10'- in which the divided flows meet in an exit flow that leaves the second spherical body -10'- through the opening 21'-, for example an outlet nozzle. The divided fluxes absorb thermal energy from the solar radiation -22 that comes from a field of heliostats (not shown in the drawings) reflected in the tubes -14- so that the salt melted or other transmission fluid is heated. HE provides a thermal protection -23- conventional per se to improve the thermal efficiency of the solar absorption panel -12--. The thermal protection -23- isolates the adsorption panel -12- and the collector -10, 10'- except in the area of the the solar absorption tubes -14- receiving the reflected solar radiation -22-.

Figures 2, 3 and 4 show a preferred embodiment of a spherical collector -10, 10'- according to this invention, in that the spherical main body -18, 18'- has a variable cross section. In this embodiment, the opening, is say, the inlet or outlet nozzle -21, 21'- and / or union nozzles -16- are preferably extruded directly from the main body -18, 18'-.

Figure 5 shows an embodiment of the collector Spherical -10, 10'- in which the nozzle -21, 21 '; 16, 16'- scjn elements made separately that have been inserted in holes previously made in the main body spherical -18, 18-and soldiers to it.

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, is claimed as a priority; content in the following: CLAIMS

1. - A solar receiver panel (12) comprising a first collector (10) with an inlet for a thermal fluid, a second manifold (10 ') with an outlet for the thermal fluid, and a plurality of solar absorption tubes (14) connected to said collectors (10, 10 '), characterized pdr that at least one of the collectors (10, 10 ') is a collector comprising a collector body (18, 18 ') comprising: a collector wall that surrounds a chamber Internal (11, 11 ') with a substantially spherical shape with a maximum cross section that is equal to or less of 1.5 times the sum of the sections of the steps of the solar absorption tubes (14) to be connected to said junction nozzles (16, 16 '), - at least one access opening (21, 21 ') communicating with the internal chamber (11, 11') to connect a fluid tube, and a plurality of junction nozzles (16, 16 ') provided in the collector wall that can be connected to the respective solar absorption tubes (14), at least one of the nozzles (16, 16) being located in a semi-spherical segment of the internal chamber (11, 11 ') which is transversely opposite said access opening (21, 21'), the access opening (21, 21 '), the internal chamber (11, 11') and the nozzles (16, 16 ') being arranged to allow a thermal fluid to flow through them

2. - A solar receiver panel according to the claim 1, characterized in that the collector body (18, 18) has an external substantially spherical shape.

3. - A solar receiver panel according to claim 1 or 2, characterized in that at least some of the junction nozzles (16, 16 ') are formed by extrusion from the collector wall,

4. - A solar receiver panel according to claim 1, 2 or 3, characterized in that at least some of connection nozzles (16, 16 ') are independent elements fixed in holes in the wall of the collector.

5. - A solar receiver panel, according to claim 4, characterized in that the connecting nozzles (16, 16 ') are fixed by welding.

6. - A solar receiver panel according to any of claims 1 to 5, characterized in that the at least one access opening (21, 21 ') is an access nozzle formed by extrusion from the collector wall.

7. - A solar receiver panel according to any of claims 1 to 5, characterized in that the at least one access opening (21, 21 ') is an access nozzle fixed in an access hole in the collector wall.

8. - A solar receiver panel according to any of claims 1 to 7, characterized in that only access opening (21) and because the sections of the internal passages of the tubes Solar (14) is at least equal to the section of the internal passage of the fluid tube to be connected to the access opening (21, 21 ').

9. - A solar receiver panel according to any of claims 1 to 7, characterized in that it comprises at least two access openings (21) and because the sum of the sections of the internal passages of the solar absorption tubes (14) is at least equal to the sum of the sections of the internal passage of the fluid tube to be connected to} access opening (21, 21 ').

10. - A solar receiver panel according to any of claims 1 to 8, characterized in that the junction nozzles (16, 16 ') are evenly distributed in the wall of the collector.