ES2394353B2 - Longitudinal solar thermal energy receiver - Google Patents

Abstract

Parallel tube receiver, contained in a housing, one of whose end walls contains all the penetrations of the tubes, which by the opposite or confined wall have no outlet, so the tubes are unequivocally matched according to their thermal function and connected to each other by means of a lyre of expansion at the end of the border, and each pair forms a fluid circuit that travels back and forth the housing along. The housing has a window composed of modules, assembled on sleepers that also give transverse rigidity to the housing, which is sealed; and whose internal pressure is kept constant thanks to individual relief valves, one acting by internal overpressure, and the other by depression.

Description

LONGITUDINAL RECEIVER OF THERMAL SOLAR ENERGY

SECTOR OF THE TECHNIQUE

The invention falls within the field of solar power plants that require concentration of the original radiation, which in this case is reflected by a series of longitudinal, horizontal or slightly inclined mirrors, and orientable by rotating around its axis of longitudinal symmetry ; focusing the radiation reflected on a similarly longitudinal receiver, with its long horizontal axis or slightly inclined, and specifically deals with the receiver that captures the concentrated radiation.

BACKGROUND OF THE INVENTION

This invention is related to two other inventions, whose inventor is the same as this application. The first one is the ES 2 321 57682 patent, consisting of a compensated expansion and pressure receiver, and the second invention is ES 2 345 759 82, in which a longitudinal collector is presented whose tubes are grouped into independent beams, central and adjacent, thermally insulated from each other longitudinally, circulating the heating fluid first through both adjacent beams in parallel, to be then injected into the central beam.

On the other hand, the international application WO 2009/029277 A2 raises a conventional Fresnel configuration with multi-tube receiver, and numerous configuration variants, although without numerical assembly requirements, and with very generic claims; and WO 2009/023063 A2 deals with a transverse inclined receiver with respect to the ground, with an asymmetric structure to favor the uptake of radiation. A more recent precedent is US2012234311A1, which presents a multitude of flow patterns in tubes, but does not address the issue of inhibiting convection around the tubes, to avoid thermal losses to the surrounding air. Of similar characteristics is the content of document W02010132849 A2.

None of the patents or applications cited addresses the problem of compensating the expansion in longitudinal distances typical of linear collectors, 100 meters or distances: higher, within a closed enclosure. These collectors fit ideally to type radiation concentrators

Fresnel, as described in the invention ES 2 345 427 82, but may

also be coupled to other concentration geometries.

TECHNICAL PROBLEM TO BE SOLVED

In the invention ES 2 321 576 82 there is presented a device to compensate for the expansion in a module or short collector drawer, the drawer in which the radiation absorbing tubes undergo a dilation when heated which is not greater than the edge is understood lower drawer crosswise. It also contains an active device to compensate for internal pressure and always keep it at a given level. In the invention ES 2 345 759 82 a set of these drawers or manifold modules are longitudinally grouped, the expansion and pressure being compensated in each module.

The aforementioned devices are useful for applications where you want to keep relative vacuum inside the drawer, or want to fill it with an inert gas, to avoid air oxidation. When it is not so harmful and it is decided to use air, particularly at atmospheric pressure, the multi-module assembly is complicated, expensive and with great loss of manometric load in the fluid, due to the numerous elbows and strangulation and widening that involve so many lyres of Expansion compensation, which in turn are the connecting elements between the successive module tubes.

Thus, the technical problem that this invention comes to solve is to present a single-casing manifold assembly, of indefinitely long length, which incorporates a passive pressure compensation device in relation to the local atmosphere without the need for active components such as the compressors, and an assimilation device for changes in length due to temperature variations in the tube bundles.

EXPLANATION OF THE INVENTION

The invention consists in configuring the solar thermal energy receiver by means of a set of tube bundles, and eventually there can be bundles of a single tube, said bundles being located entirely inside a parallelepiped shaped housing, said tubes extending along of the housing, and filling the tube bundles the width of the housing, of which five of the walls are solid, mechanically resistant and insulated

thermally, and one of them is open, but it is joined by a transparent window with perimeter fence of similar or equal material to the housing, said window being constituted by successive modules mounted longitudinally, each module being constituted by a solid fence to which the transparent window is adhered by a seal of silicone or other closure material, and there are crossbars or sleepers on the open face of the parallelepiped of the housing corresponding to the window, said stringers conferring mechanical resistance to the side walls of the housing, being in turn support pieces of the successive window modules by their longitudinal ends, there being also a square-shaped piece along the entire open perimeter of the side walls and the ends of the housing, with the which square piece adjusts the fences of the window modules; the tube bundles being supported on crossbars suspended by cables or braces from the upper or back wall of the housing, which is the opposite of the face of the parallelepiped that contains the window, and the tube bundles being fixed at one end to the wall of the end of the carcass that acts as the head wall of the carcass, and is where all the heating fluid pipes enter and exit; the tube bundles being unequivocally designated as pairs, two by two, according to the thermal function they perform, and the pairs of tube bundles being joined at the opposite end of the header by means of U-shaped pieces or semicircular shapes warped, with rotation in more than one spatial direction, leaving the wall opposite to the headboard, or confined, closed and sealed wall, enabling in said boundary a length of the housing, or length of the boundary, in which there is space to accommodate the greatest variation in length that occurs in any tube, due to temperature variations that occur in the operation of the solar installation.

The allocation of tube bundles in pairs depends on whether the heating is only sensitive, without phase change, or boiling, with liquid preheating and superheating of the steam produced.

For the assignment of the beams, those of the same function are paired, taking into account that much hotter tube areas than others have to be avoided, so that the beams with a higher film coefficient of the fluid inside are located in the longitudinal bands of the receiver that receive a higher level of concentrated radiation. It is also necessary to have the temperature that the internal fluid has to reach in each thermal function, since there is a thermal flux value below which, it cannot be reached with a given fluid at a given temperature, or it is reached with very high performance low.

Each tube bundle is longitudinally insulated by partitions of thickness similar to the thickness of the pipes, from the dorsal or upper wall of the housing to the widest part of the beam, the partitions being able to go through pipes connected between bundles of the same pair, when they are on each side of the longitudinal plane of symmetry, to ensure similarity of thermal evolutions in both beams.

To maintain the pressure at the local atmospheric level, the wall of the housing is drilled with a plurality of ducts that are provided with relief valves, directed in one direction or another, so when the pressure inside the interior rises waterproof housing, due to the increase in temperature, it is relieved by expelling air from the interior into the atmosphere through the overpressure valves; and when the pressure inside the housing decreases, the air enters the atmosphere by opening the depression relief valve in that direction.

EXPLANATION OF THE FIGURES

Figure 1 shows a diagram, in straight section, of bundles of receiver tubes, their thermal insulation partitions, the suspended bars that support the tubes, and the window with its fence and joints. Relief valves in their ducts and lugs or brackets for fixing the housing to the general clamping structure are also shown.

Figure 2 shows the longitudinal scheme of the receiver, with the header wall on the left and the border on the right; and the cut of several sleepers, as well as the bars of subjection, including those of the space of the border.

Figure 3 shows an upper longitudinal scheme of a collector with 10 beams paired two to two, as well as the confine space and the U-joints.

Figure 4 shows the longitudinal scheme of a double U lyre concatenated vertically / obliquely and obliquely / horizontally.

..

Figure 5 shows the scheme in straight section of a crossbar

housing frame and clamping glass modules. Figure 6 shows an upper longitudinal diagram of a manifold for heating fluid that does not change phase as it passes through the receiver. There are 8 beams paired two to two, as well as the confine space and the U-joints.

EMBODIMENTS OF THE INVENTION

In order to facilitate the understanding of the figures of the invention, and of their embodiments, the relevant elements thereof are listed below:

one . Receiver housing

2.

Glass or transparent window material.

3.

Surrounding the window.

Four.

Perimeter square of the housing to receive the window.

5.

Window seal.

6.

Window strap clamp.

7.

Support bar braces (8).

8.

Support bars of the tubes. One way tube of the central circuit, pair of 10.

10.

Return tube of the central circuit, pair of 9, with which it constitutes said circuit.

eleven.

One of the semi-circuit tubes of the intermediate circuit.

12.

Semi-circuit tube of the intermediate circuit, which with the tube 11 constitutes said semi-circuit.

13.

One of the half-return tubes of the intermediate circuit.

14.

Tube of the intermediate return circuit of the intermediate circuit, which with the tube 13 constitutes said semi-circuit, which forms even with the halfway circuit formed by the tubes 11 and 12.

fifteen.

Outflow tube of the left side circuit, pair of 16.

16.

Return tube of the left side circuit, pair of 15, with which

It constitutes said circuit.

17.

Outlet tube of the right side circuit, pair of 18.

18.

Return tube of the right side circuit, pair of 17, with which it constitutes said circuit.

19.

Separating and insulating screens between bundles of different circuit tubes.

twenty.

Transverse pipe of homogenization of tubes of the same semi-circuit.

twenty-one.

Additional support bar braces in the confined space (22).

22

Pipe support bars, additional in the confined space.

2. 3.

Ears or brackets for holding the housing.

24.

Inner overpressure relief tube.

25.

Relief tube for internal depression.

26.

Naughty armor of the housing and clamping of the glass modules.

27.

Window module

28.

Upper or back wall of the housing.

29.

Head wall with all the penetrations of the tubes.

30

Confined wall, without penetration, except the relief valve ducts.

31.

Lira dilatation and contraction,

32

Union in simple U.

33.

Semi-circuit collector of the intermediate circuit.

3. 4.

Semi-return circuit collector of intermediate circuit.

35

Space line for joining the return (33) and return (34) collectors of the intermediate circuit.

36.

Space lane for joining the return and return tubes of the left lateral circuit.

37.

Space lane for joining the return and return pipes of the side circuit

straight.

38.

Inlet duct in a conjoined and warped double U-shaped space lyre.

39.

Exit duct in a conjoined and warped double U-shaped space lyre.

40

Generic tube.

41.

Penetration of a generic tube through the head, integral to it.

42

Penetration of conduit or inlet tube of the flow to the tube bundle 9 through the head, integral with it.

43

Penetration of conduit or evacuation tube from the flow of the tube bundle 10 through the head, integral with it.

44.

Other duct penetrations.

Four. Five.

Support joints of the window modules (27) on the wings (46) of the sleepers (26).

46.

Wings of the sleepers (26).

47

Inlet of heating fluid that does not change phase.

48.

Output of heating fluid that does not change phase.

49.

U-connection in the header wall.

fifty.

Fluid drain pipe from the U-piece (49).

51.

Gas ejector, in space liras (31).

52

Beam of tubes or inlet duct in the series circuit on the left side.

53.

Beam of tubes or outlet duct in the series circuit on the left side.

54. Beams of intermediate tubes in the series circuit on the left side. The invention is embodied by assembling a set of parallel tubes or conduits, of the appropriate length to the field of mirrors that it sends

the reflected radiation, inside a rigid and thermally insulated housing, with mechanical resistance to withstand the weight of said tubes, filled with fluid

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heater. The housing is shaped like a very long parallelepiped, and one of its wide and long faces is devoid of a wall. Throughout this non-existent wall perimeter, the housing has a rigid square (4), under which a silicone or resin joint of similar characteristics is adhered, against which the corresponding window module, composed of of an equally rigid fence (3) and with silicone gasket, and the glass module (27). These modules are much shorter in length than the housing, which can measure 100 meters or more, while the window module is about 5 meters long. To fix said modules, sleepers (26) are used that go from side to side of the housing section, giving rigidity to the above perimeter of the open part of the housing. These sleepers have an inverted T-shape, with the trunk of the T welded or attached at its ends to the bottom of the side walls of the housing. The wings of the T (46), which remain in the lower part, serve as flaps to receive the ends of the fences of the window modules. The window modules are in turn coated with silicone on the side part of the fence, and also, or alternatively, pressed to the perimeter square (4) of the housing by means of strap clamps (6).

All the penetrations (41) of the tubes enter and exit through the head wall (29), all these penetrations being firm, without displacements of the tubes in the head; which are laid along the housing, supported by crossbars (8) suspended from the dorsal or upper wall of the housing, by means of braces (7). Between bundles of tubes or tubes with different thermal functions, a rigid insulating screen (19) is installed, of small thickness, even smaller than the thickness of the tubes, which reaches from the dorsal wall (28) to the area of maximum width of the tube bundle to insulate.

Each tube or bundle of tubes, in one application, has an assigned thermal function, specified in being part of a half-circuit, one way or return, of a given circuit; which makes the tube bundles (including if they are monotubes) are designated by pairs, which are the semi-circuits in question; the circuit being closed on the side of the boundary (30), by means of a U (32), if the expected deformation of said semi-circuits is similar, as is the biphasic case in which there is boiling, and therefore with very uniform temperature ; or closing with expansion lyres (31), with spatial configuration, similar to several U concatenated.

There are many possible variants that can be addressed with this

invention, thanks to the type of arrangement of the tubes, with a header and a confinement, in which there is space and configuration of the tubes to allow their length changes.

For example, for boiling assemblies of a liquid, the invention is mounted with four circuits, two corresponding to the sides of the receiver, for the preheating of the liquid, in the strips with a lower level of concentrated radiation, being located separately, such as is shown in figure 3; to avoid a complex connection from one side of the housing to the other, across it, at the end; whereby space lira paths (36 and 37) are available to close each of the said circuits.

The next circuit in the order of temperature is that of boiling, which is located in the center, with a one-way (9) and a return (10) conduit, since the boiling has the highest film coefficient, and therefore can accommodate a high value of the intensity of the concentrated radiation without requiring much surface or much temperature difference between the radiation receiving surface and the boiling fluid.

and the third circuit in thermodynamic order, which is geometrically intermediate in figure 3, is that of steam overheating, composed in that figure by two tubes in each semicircuit, on opposite sides of the case both way (11 and 12) as of return (13 and 14), joining the semicircuitos first each one by himself, and then these to each other through a space lira (35), that develops to two levels of height, what demands some additional suspension bars ( 22).

In the case of applications in which the heating fluid does not change phase, the assembly is simplified, and each tube bundle is located adjacent to its pair, joined at the end by a space lyre (31). For reasons of symmetry, as shown in Figure 6, there is an even number of circuits, and half of the circuits, corresponding to one of the sides of the housing, can go in parallel, so that each circuit has its own fluid inlet and outlet through the header, or they can be mounted in series, in this case there is only one inlet (47) and one outlet (48) for each half of the housing, the successive circuits being linked through a joint U-shaped (49) in the header wall (29).

Eventually, the heating fluids may have a very high solidification point, whereby it is possible to evacuate the fluid from the solar receiver circuit, and send it to a conveniently insulated tank. For this, the tube bundles are mounted with a small inclination, leaving the

5 header (29) at a lower level than the border wall (30), with the extraction of the fluid by the header; that in case of having U-joints connecting two contiguous penetrations, said unions must have in their lower part a tube, equipped with an opening-closing valve, to drain the fluid.

Both in the case of boiling fluids and in the fluids that

10 remain as liquids, a non-condensable or soluble gas ejector (51) is disposed in the highest part of the expansion lyres (31), which is evacuated to the interior space of the housing. Note that the internal pressure of the housing is relaxed if it exceeds the overhead of the overpressure relief valve (24), said pressure value being higher than the local atmospheric pressure, and

Preferably greater than 10% of said pressure; the internal depression opening valves (25) being set to open when the internal pressure drops below 90% of the local atmospheric pressure. Although it has been defined that the confined wall is closed, in the sense that no tube passes through it, the penetrations of the valves of the valves can be placed in it.

20 relief from overpressure and depression.

Once the invention is clearly described, it is noted that the particular embodiments described above are subject to modifications in detail as long as they do not alter the fundamental principle and essence of the invention.

Claims (1)

1 Longitudinal solar thermal energy receiver, consisting of a

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plurality of parallel tube bundles, possibly having single-tube bundles, said bundles being located entirely inside a housing characterized in that the housing is in the form of a parallelepiped, said tubes extending along the inside of the housing (1) , and filling the tube bundles with the width of the housing, of which five of the walls are solid, mechanically resistant and thermally insulated, and one of them is open, but it is joined by a transparent window (2) with fence perimeter (3) of material similar or equal to that of the housing, said window being constituted by successive modules (27) mounted longitudinally, each module being constituted by a solid fence (3) to which the transparent window is adhered by a joint (5 ) of silicone or other closure material, and there are transverse or crossbar stringers (26) in the open face of the parallelepiped of the housing corresponding to the window, said stringers conferring mechanical resistance to the lateral walls of the housing, in turn being support pieces of the successive window modules (27) at their longitudinal ends, there being also a square-shaped part (4) along the entire open perimeter of the side walls and the ends of the housing, with the which square piece adjusts the fences of the window modules; the tube bundles being supported on crossbars (8) suspended by cables or braces (7) from the upper or back wall (28) of the housing, which is the opposite of the face of the parallelepiped that contains the window, and being the bundles of tubes fixed at one end to the wall of the end of the housing that acts as the head wall (29) of the housing, and that is where all the heat fluid tubes enter and exit, the tubes being solidly attached to the head of the housing in the penetrations (41, 42, 43, 44); And the tube bundles being unequivocally designated as pairs, two by two, according to the thermal function they perform, and the pairs of tube bundles being joined at the opposite end of the header by means of U-shaped pieces or Lira of warped semicircular shapes, with rotation in more than one spatial direction, leaving the wall opposite to the headboard, or confined wall (30), closed and sealed, enabling in said confinement a length of the housing, or length of the boundary, in which there is space to accommodate the greatest variation in length that occurs in any tube, due to temperature variations that occur in the operation of the solar installation. 2 Longitudinal solar thermal energy receiver, according to claim

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first, characterized in that each tube bundle is longitudinally insulated by partitions (19) of thickness similar to the thickness of the tubes, from the dorsal or upper wall (28) of the housing to the widest part of the beam, the partitions being able to go crossed by connecting tubes (20) between beams of the same pair, when they are on each side of the longitudinal plane of symmetry, to ensure similarity of thermal evolutions in both beams. 3 Longitudinal solar thermal energy receiver, according to any of

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the preceding claims, characterized in that the wall of the housing is drilled with a plurality of conduits that are provided with relief valves, directed in one direction or another, so that when the pressure inside the waterproof housing rises, due when the temperature rises, it is relieved by expelling air from the interior into the atmosphere through the overpressure valves; and when the pressure inside the housing decreases, the air enters the atmosphere by opening the depression relief valve in that direction; the overhead of the overpressure relief valve (24) being greater than the local atmospheric pressure, and preferably greater by 10% of said pressure; the internal depression opening valves (25) being set to open when the internal pressure drops below 90% of the local atmospheric pressure. 4 Longitudinal solar thermal energy receiver, according to any of

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The preceding claims, characterized in that the beams with a higher film coefficient of the fluid inside are located in the longitudinal strips of the receiver that receive a higher level of concentrated radiation. S Longitudinal solar thermal energy receiver, according to any of

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The preceding claims, characterized in that the sleepers (26) that give rigidity to the perimeter of the open part of the housing have an inverted T-shape, with the trunk of the T welded or attached at its ends to the lower part of the side walls of the housing: serving the wings of the T (46), which remain in the lower part, of flaps to receive the ends of the fences of the window modules (27). 6 Longitudinal solar thermal energy receiver, according to any of

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The preceding claims, characterized in that the lateral part of the window modules fence (27) is pressed to the perimeter square (4) of the housing by means of strapping clamps (6). 7 Longitudinal solar thermal energy receiver, according to any of

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The preceding claims, characterized in that a gas ejector (51) is disposed in the highest part of the expansion lines (31) or in the U-connection pieces (35) in the confine space, which evacuate to the interior space of the housing. 8 Longitudinal solar thermal energy receiver, according to any of

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The preceding claims, characterized in that in the assemblies with boiling of a liquid, the invention is mounted with four circuits, corresponding two to the sides of the receiver, for the preheating of the liquid, in the strips with lower level of concentrated radiation, being located by separated, and the semicircuits of each circuit being closed by space expansion lyre paths (36, 37); the following circuit being the boiling one, which is located in the center of the receiver, with a one-way (9) and a return duct (10), closed by a piece in a U (32); And the third circuit being that of steam overheating, consisting of two tubes or bundles of tubes in each semicircuit, on opposite sides of the housing, symmetrical with each other the tubes of each semicircuit, both outward (11, 12) and return (13,14), joining first the semicircuitos each one by himself, and then these to each other through a space lira (35), that develops to two levels of height, what demands some additional suspensor bars (22). 9 Longitudinal solar thermal energy receiver, according to any of

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the preceding claims, characterized in that in the case of applications in which the heating fluid does not change phase, each bundle of tubes is located adjacent to its pair, joined at the end by a space lyre (31) and for reasons of symmetry, there is an even number of circuits, and half of the circuits, corresponding to one of the sides of the housing, can go in parallel, so that each circuit has its inlet (47) and its outlet (48) of fluid to through the header (29), or they can be mounted in series, in this case there is only one input and one output for each half of the housing, the successive circuits being linked through a U-joint (49) in the header wall. 10 Longitudinal solar thermal energy receiver, according to any of

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The preceding claims, characterized in that when the heating fluids have a very high solidification point, during the night or in long periods without sun, the fluid from the solar receiver circuit is evacuated, and drained to a suitably insulated tank, for which tube bundles are mounted with a small inclination, the head (29) being at a lower level than the border wall (30), the extraction of the fluid being carried out by the head; that in case of having U-joints connecting two adjacent penetrations, said joints must have a tube (50) in its lower part, provided with an opening-closing valve, to drain the fluid.