KR20020055870A - Central solar receiver - Google Patents

Abstract

PURPOSE: A central solar receiver is provided to simplify the design and prevent the improper restraint of a window. The receiver is proper to use at high temperature and under high pressure. CONSTITUTION: A central solar receiver includes an axially symmetrical housing(1) having front and rear ends(3,6) and an opening(4) formed in the front end, a long tubular window(10) mounted in the opening concentric with the housing and having an opened front end(11) fixed to the opening of the front end of the housing, a closed rear end(12) adjacent to the rear end of the housing but not fixed to the housing, a first surface(16) facing incident and concentrated sunlight, and a second surface(18) facing the inside of the housing, volumetric sunlight absorbing elements(50,52) disposed in the housing and extended around the window for absorbing sunlight passing through the window, and a pair of fluid inlet and outlet formed in the housing for the injection and recovering of a working fluid for correlated operation between the volumetric sunlight absorbing element with working fluid.

Description

Centralized Solar Collector {CENTRAL SOLAR RECEIVER}

The present invention relates to a concentrated solar collector, and more particularly to a window used in such a collector for receiving and passing concentrated sunlight.

The present invention provides a concentrated solar system comprising a housing having a solar absorber adapted to absorb concentrated sunlight at temperatures, in particular at high temperatures, usually at or above 500 ° C., and a working fluid circulating therein in an indirect or direct heat exchange relationship with the solar absorber. Relates to a light collector. The housing of such a solar collector is formed with an opening disposed in the focal region of the solar concentrating system, and has a window adapted to receive the highly concentrated sunlight from the concentrating system and pass it towards the solar absorber.

Solar absorbers used in this type of concentrated solar collector are often volumetric solar absorbers made in the form of a three-dimensional matrix that allows the working fluid to flow and transfer heat to the working fluid. Such solar collectors are described, for example, in Israel patent 97091 and US patent 5,323,764.

Working fluids used in concentrated solar collectors are usually provided as heat carrier fluids or designed to conduct heat induced endothermic chemical reactions that affect the possible catalysis between components of the working fluid.

For various industrial applications, such as the operation of electricity generating gas turbines or the carrying out of certain types of endothermic reactions, it is necessary to allow the working fluid to circulate through the system at high pressures of at least about 2 atmospheres. At such pressures, the density of the working fluid in the circulating gas state is higher than when it is in an uncompressed state, so that the pressure loss during circulation is lower.

One of the most important problems associated with pressurized concentrated solar collectors with windows is the mechanical strength of the windows. Materials with the required optical and thermal properties are brittle and can tolerate large compressive stresses, while tending to break or crush under relatively small stresses. The stress in the window is formed by thermal expansion and other collector elements in contact with the window that are non-uniform with the gas pressure inside the collector when heated during operation.

US Pat. Nos. 5,323,764 and 5,421,322 disclose centralized solar collectors with truncated conical windows having front large and rear small diameter open ends formed of cylindrical front and rear rims with windows fixed at the front and rear ends to the housing. . An annular positioning groove is formed at the front end of the housing and the front rim of the window is received therein and fixed by the O-ring. The rear rim of the window is fixed in the metal block, in particular the metal block comprises a thermal expansion absorbing bellows and a reflector configured to protect the bellows and the block from the aggregated sunlight entering the window.

It is an object of the present invention to provide a new window for use in a centralized solar collector and a new centralized solar collector using the same.

According to one aspect of the invention there is provided an asymmetric housing having a) a front end and a rear end, and an opening at the front end; and b) an open front end fixed to the housing at the front end of the housing and a rear end of the housing. An elongated tubular window mounted coaxially with the housing within said opening, having a closed rear end that is not secured to the housing adjacent to, a first surface facing the incident and concentrated sunlight and a second surface facing the interior of the housing; c) a volumetric solar absorber disposed within the housing and extending around and along the elongated window to absorb the sunlight passing therethrough; and d) formed in the housing so that a working fluid is formed in the volume. To inject and withdraw pressurized working fluid into the housing in a manner that allows interaction with the solar absorber; The centralized solar collector is provided which comprises a copper fluid inlet and outlet.

According to another aspect of the invention, it has an elongated tubular shape with an open front end adapted to pass incident and highly concentrated sunlight into the collector, and an open front end adapted to be fixed to the opening of the collector and a closed rear end without any fastening means, A window is provided for use in such a concentrated solar collector.

The design of the window of the present invention and the method of mounting the window to the centralized solar collector, whereby the window is fixed only at the front end, simplify the design of the collector and prevent the window from being undesirably constrained, which can be used at high temperatures and pressures. To suit.

Preferably, the window is truncated conical, the open front end of which has a large diameter end, and the closed rear end has a small diameter end. However, the window may have any constriction-symmetrical shape, for example cylindrical, where the front end is formed of a rim having a larger diameter than other portions of the window.

Preferably, the front end of the window is an elastic mounting device such as a spring loaded clamp that permanently exerts an axial force on the window body that holds the window in place and prevents its movement under its action during heat and pressure cycles when the collector is operated. Is fixed to the housing.

Preferably, the rear closed small diameter end of the window is in the form of a cap-shaped concave surface which is continuously joined with the conical surface of the window. These closed ends and truncated cones of the window body generate compressive stresses rather than tensions that can cause any pressure exerted on the window from within the housing to create a force component that acts vertically along the surface of the window to break the window.

Preferably, the working fluid inlet is positioned adjacent the rear end of the housing coaxial with it so as to face said closed end of the window. Further solar absorbers are more preferably mounted in the housing between the working fluid inlet and the closed end of the window to absorb concentrated sunlight passing through the closed end. As such, the working fluid inlet is protected from direct penetration of concentrated sunlight and is preheated as it enters the collector prior to interaction with the volumetric solar absorber. The further solar absorber may also be a volumetric solar absorber.

DETAILED DESCRIPTION In order to understand the present invention and to understand how it may be practiced, embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings.

1 is a schematic cross-sectional view of a concentrated solar collector according to the present invention.

FIG. 2 is an enlarged view of region A of the collector shown in FIG.

<Explanation of symbols for the main parts of the drawings>

1: housing

3: front end

6: rear end

10: window

11: front opening large diameter end

12: rear closed small diameter end

13: window body

50: first absorber

52: second absorber

53: Collector Chamber

58: working fluid inlet duct

60: working fluid outlet chamber

The centralized solar collector of the present invention, as shown in FIG. 1, is designed in connection with a solar focused system (not shown) and has a longitudinal axis X, a hole 4 therein facing the centralized sunlight. And a front end 3, a rear end 6 and an outer wall 8 having a front end 3. The collector further comprises an elongated tubular window 10 mounted in a hole 4 coaxial with the housing 1, the window configured for the reception of highly concentrated sunlight from the solar concentration system and capable of withstanding high temperatures. have. For this purpose, the window can be made of any conventional material having certain optical and thermal properties, such as fused quartz, for example.

The window 10 has a front open large diameter end 11, a rear closed small diameter end 12, and a truncated conical window body 13 between them, the first surface 16 being faced by incident and concentrated sunlight. And the second surface 18 faces the interior of the housing 1. The window body 13 has a circular cross-sectional shape, but this shape may take other preferred forms. In addition, the window body may be cylindrical in the form of a rim with a front large diameter end. If desired, the window 10 may take the form of a double glazing with a gap between the inner and outer windows.

The window 10 is held alone in the housing 1 by its large diameter end 11, which is adapted to be fixed to the opening 4 at the front end 3 of the housing 1 as shown in detail in FIG. 2. The front end 3 of the housing is formed of an annular groove 20 with a groove bottom with an annular seal 22 and a groove side wall 24. The large diameter end 11 of the window is secured to the annular groove 20 by a plurality of adjustable spring loaded mounting devices 30 (only one shown in FIG. 2) located along the periphery of the opening 4 of the housing. Each mounting device 30 comprises a mushroom clamp 40 having a leg 42 with an eccentric head 41 and a skirt 43. The head 41 of the clamp 40 has a truncated cone-shaped periphery to fit the contour of the frusto-conical body 13 of the window 10 and is configured by a soft ceramic rope 44 configured to contact it without damaging the window. Lining. The skirt 43 of the clamp 40 is held between the circular first spring 45 and the flange 46 pressed by the second spring 48. The clamp 40 applies the appropriate pressure to the window 10 by rotating the clamp around its axis until the rope 44 of the eccentric head 41 is adjacent to the second surface 18 of the window body 13. Fixed, springs 45 and 48 are designed to maintain this pressure permanently. Due to the conical shape of the window body 13, the pressure creates an axial force that pushes the window from the bottom of the annular groove 20 toward the seal 22, keeping the window in place and the collector When activated, it prevents the window from moving under the action of forces acting upon it during thermal and pressure cycles.

The rear closed small diameter end 12 of the window 10 is in the form of a cap-like surface that smoothly merges with the frustoconical body 13 of the window. Since the small diameter end 12 does not have any fastening means, its cap-like surface may take any desired shape, for example concave, spherical or non-spherical, or may not be flat.

The collector has a first tubular volume absorber 50 extending around and facing the frustoconical body 13 of the window 10 and a second disk disposed at the rear of the housing and facing the closed end of the window 10. It further comprises a mold volume flow-through solar absorber (52). The absorbers 50, 52 together with the second surface 18 of the window 10 form the collector chamber 53.

The first volumetric absorber 50 defines a truncated conical base 54 with an array of spiked absorbing members 56 projecting from one side of the base 54 toward the window 10 and spaced apart from each other. Have However, the absorber 50 can be of any other suitable design. For example, it may have a polyhedron-prism shape, a cylindrical shape, a parabolic shape, an elliptic shape, and the like, rather than a truncated cone. The spike shape of the absorbent member 56 is not critical and may be any suitable shape such as, for example, rods, hollow cylindrical tubes, truncated cones, plates, and the like.

The second volumetric absorber 52 may have a design similar to that described above for the absorbent body 50, with the difference that the base body of the absorbent body 52 must be perforated or designed to pass the working fluid through. For example, it may be of any other suitable form such as honeycomb, lattice, wire mesh, foam, and the like. The parallel disk shape of the volumetric solar absorber 52 is not critical, and any other suitable shape may be used. For example, the absorber 52 may be in the form of a dome or in the form of a disk having non-parallel faces, in the form of a disk with a bore or the like.

Each absorbent 50, 52 may be made of any suitable heat resistant material, such as ceramic material, ceramic coated metal alloy, silicon carbine, alumina, special stainless steel, nickel alloy and the like.

The collector further comprises a working fluid inlet duct 58 located coaxially at the rear end 6 of the housing for entry of the working fluid into the collector chamber 53. Duct 58 has an entry funnel 59 having a lateral dimension that is greater than the lateral dimension of the closed end 12 of the window. The second volumetric absorber 52 described above is preferably mounted to a funnel 59, in which the duct 58 is protected from concentrated sunlight passing through the window at the closed end 12 and all working fluid is collected in the collector chamber ( 53) it is ensured to be preheated to some extent by the miniature absorber 52 before being injected into.

The collector further comprises a working fluid annular outlet chamber 60 surrounding the entry funnel 59, the outlet chamber being on the back of the large volume solar absorber 50 to remove the working fluid from the collector chamber 53. It has an annular discharge orifice 62 positioned and a tubular discharge vent 64.

The working fluid used in the concentrated solar collector of the present invention is preferably a gas such as air adapted to circulate in the collector chamber 53 at high temperature (at least about 500 ° C.) and at a high pressure of at least about 2 atmospheres. The working gas may be of any kind suitable to serve as a heat carrier for the removal of heat generated in the solar absorber. In addition or as an alternative, the working gases may consist of a mixture of two or more components introduced to react with each other upon contact with a hot solar absorber, ie to carry out a thermochemical process. In the latter case, the protruding member 56 of the volume absorber 50 may be coated with a suitable catalyst.

It should be appreciated that the geometry of the inlet and outlet of the pressurized working fluid need not be described above, but rather can be modified to meet specific design requirements.

The housing 1 fills all the volume between the base 54 of the first volume absorbent body 50 and the housing outer wall 8 and defines the inlet duct 58, the outlet vent 64 and the angular outlet chamber 60. Furthermore, it further includes the surrounding insulating material 65.

In operation, concentrated sunlight enters through the large diameter end 11 of the window 10. Most of this light passes through the truncated conical body 13 of the window and contacts the absorber member 56 of the first volumetric solar absorber 50. Incident sunlight that has not passed through the window body 13 passes through the closed rear end 12 of the window and contacts the second volumetric solar absorber 52. Thereby, the solar absorbers 50 and 52 are heated.

The pressurized working fluid is injected into the absorber through the inlet duct 58 and the inlet funnel 59, in which case the working fluid flows through the second volume absorber 52 and before entering the collector chamber 53. It is heated to some extent. After passing through the second absorbent 52, the working fluid flows towards and along the closed end 12 of the window and then further along the frustoconical body 13, whereby the window is completely along its surface. Is cooled. The same effect is achieved with a window having the above-described double-window design, in which the working fluid flows along the gap between the windows by providing a suitable fluid passage in the inner window of the window at the front and rear ends of the window.

After approaching the region of the collector chamber 53 adjacent the front end 3 of the housing, the working fluid flows through the volumetric absorber 50 across the array of members 56 in a direction, in which The working fluid is heated or involved in endothermic chemical reactions. The heated working fluid and reaction product are further introduced into the annular outlet chamber 60 through the outlet orifice 62 and exit through an outlet vent 64 for operating the power generating turbine, for example.

During operation, any movement of the window 10 relative to the absorber housing is compensated for by the spring loaded mounting device 30. Any thermal expansion of any absorber element, symmetrical or asymmetrical, is only set at the large diameter end 11 and thus is not transmitted to the window 10.

It should be understood that the foregoing embodiments are merely one embodiment of the concentrated solar absorber and window used herein in accordance with the present invention and that the scope of the invention as set forth in the claims fully includes other embodiments that may be apparent to those skilled in the art. .

According to the present invention, the design of the solar collector is simplified and the window is undesirably constrained, making the solar collector suitable for use at high temperatures and pressures.

Claims (20)

a) an axisymmetric housing having a front end and a rear end and an opening at the front end; b) an open front end fixed to the housing at the front end of the housing and a closed rear end not fixed to the housing adjacent to the rear end of the housing, the first surface facing the incident and concentrated sunlight and the interior of the housing; An elongated tubular window having a second surface facing and mounted coaxially with the housing within the opening; c) a volumetric solar absorber disposed within said housing and absorbing sunlight passing through and extending around said elongate window; d) a working fluid inlet and outlet for injecting and withdrawing the pressurized working fluid into the housing and formed in the housing to enable the working fluid to interact with the volumetric solar absorber. Featured solar collector. The centralized solar collector of claim 1, wherein the front end of the window is secured to the housing by an elastic mounting device located around the opening of the housing. The centralized solar collector of claim 2, wherein the mounting device is a spring loaded clamp. 4. The concentrated solar collector of any one of claims 1 to 3, wherein the rear closed end of the window has a concavely curved shape, such as a cap. 5. The centralized solar collector of claim 1, wherein the rear closed end of the window is flat. 6. The centralized solar collector of claim 1, wherein the working fluid inlet is positioned coaxially with the housing adjacent the rear end of the housing toward the closed end of the window. 7. 7. The centralized solar collector of claim 6, comprising an additional solar absorber mounted in the housing between the working fluid inlet and the closed end of the window. 8. The concentrated solar collector of claim 7, wherein the additional absorber has a lateral dimension that is greater than the lateral dimension of the closed end of the window to absorb concentrated sunlight passing through the closed end of the window. 9. The concentrated solar collector of claim 8, wherein the additional volumetric absorber has a passageway through which working fluid flowing from the inlet can pass. 10. The centralized solar collector of claim 9, wherein the inlet is in the shape of a conduit with a front funnel and the additional volume absorber is mounted in the funnel. The concentrated solar collector of claim 7, wherein the further volumetric absorber is generally disc-shaped. 12. The concentrated solar collector of claim 1, wherein the window has a frusto-conical body. 12. The centralized solar collector of any one of claims 1 to 11, wherein the window is in the form of a rim in which the front end has a larger diameter than the diameter of the cylindrical body. The centralized solar collector of any one of the preceding claims, wherein the window is in the form of a double glazing. A window adapted for use in a concentrated solar collector having an opening at the front end, The window has an elongated tubular shape having an open front end adapted to be secured to the opening of the collector and a closed rear end without any fastening means, the window being mounted in the opening to allow incident and highly concentrated sunlight to pass into the collector. The window characterized in that. A window as claimed in claim 15 having a truncated cone body. The window of claim 15, wherein the front end has a cylindrical body in the form of a rim having a larger diameter than the diameter of the cylindrical body. 18. The window according to any one of claims 15 to 17, wherein the window is in the form of a double glazing. 19. A window according to any one of claims 15 to 18, wherein the closed end of the rear of the window has a concavely curved cap shape. 19. A window according to any one of claims 15 to 18, wherein the closed end of the rear of the window is flat.