Heat receiver tube, method for manufacturing the heat receiver tube, solar collector with the heat receiver tube and method for producing electricity by using the solar collector

Abstract

A heat receiver tube for absorbing solar energy and for transferring absorbed solar energy to a heat transfer fluid which can be located inside of at least one core tube of the heat receiver tube is provided. The core tube includes a core tube surface with at least one solar energy absorptive coating for absorbing solar radiation. The core tube is enveloped by at least one enveloping tube. The enveloping tube includes at least one enveloping tube wall which is at least partly transparent for the solar radiation. The enveloping tube wall includes at least one inner enveloping tube surface. The core tube and the enveloping tube are coaxially arranged to each other such that an inner heat receiver tube space is formed which is bordered by the core tube surface (and the inner enveloping tube surface.

Claims

1. A heat receiver tube for absorbing solar energy and for transferring absorbed solar energy to a heat transfer fluid which can be located inside of at least one core tube of the heat receiver tube, wherein the at least one core tube comprises a core tube surface with at least one solar energy absorptive coating for absorbing solar radiation; the at least one core tube is enveloped by at least one enveloping tube; the enveloping tube comprises at least one enveloping tube wall which is at least partly transparent for the solar radiation; the enveloping tube wall comprises at least one inner enveloping tube surface; the at least one core tube and the enveloping tube are coaxially arranged to each other such that an inner heat receiver tube space is formed which is bordered by the core tube surface and the at least one inner enveloping tube surface; and the heat receiver tube comprises at least one pressure adapting device for adapting a space pressure of the inner heat receiver tube space compensating to an environmental pressure of an environment of the heat receiver tube.

2. The heat receiver tube according to claim 1, wherein the space pressure comprises a partial pressure of hydrogen.

3. The heat receiver tube according to claim 1, wherein the at least one pressure adapting device comprises at least one opening for connecting the inner heat receiver tube space and the environment.

4. The heat receiver tube according to claim 3, wherein the opening comprises an opening dimension which is selected from the range between 1 mm and 20 mm.

5. The heat receiver tube according to claim 1, wherein the enveloping tube wall comprises glass.

6. The heat receiver tube according to claim 1, wherein the heat receiver tube comprises at least one dimension device with a flexible device wall for compensation of a thermally induced change of at least one dimension of the heat receiver tube.

7. The heat receiver tube according to claim 6, wherein the device comprises bellows and the flexible device wall comprises a bellows wall.

8. The heat receiver tube according to claim 7, wherein the bellows are arranged at a front side of the heat receiver tube.

9. The heat receiver tube according to claim 6, wherein the enveloping tube and the dimension device are covered by at least one heat receiver tube skirt with at least one heat receiver tube skirt wall.

10. The heat receiver tube according to claim 6 wherein the flexible device wall and/or the heat receiver tube skirt wall comprise at least one metal.

11. The heat receiver tube according to claim 1, wherein the enveloping tube wall and/or the bellow wall and/or the heat receiver tube skirt wall comprise the pressure adapting device.

12. The heat receiver tube according to claim 1, wherein the pressure adapting device comprises at least one particle filter for avoiding an infiltration of particles of the environment into the inner heat receiver tube space.

13. The heat receiver tube according to claim 12, wherein the particle filter comprises at least one ceramic material.

14. Method for manufacturing a heat receiver tube with following steps: a) providing of at least one heat receiver tube; and b) arranging of at least one pressure device at the at least one heat receiver tube for allowing air of an environment surrounding the heat receiver tube to be guided into the heat receiver tube for compensating a space pressure.

15. The method according to claim 14, wherein the arranging of the pressure device comprises a drilling of a hole into at least one of the walls of the heat receiver tube.

16. A solar collector comprising at least one mirror having a sunlight reflecting mirror surface for directing sunlight to a focal line of the sunlight reflecting mirror surface; and at least one heat receiver tube according to claim 1 which is arranged in the focal line of the sunlight reflecting mirror surface.

17. The solar collector according to claim 16, wherein the mirror is a parabolic mirror or a Fresnel mirror.

18. The method for producing electricity by using the solar collector according to claim 15 in a solar thermal power plant for converting solar energy into electrical energy, wherein an absorbing of the sunlight energy is carried out with the aid of the solar collector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows cross sections of a heat receiver tube;

(3) FIG. 2 shows cross sections of a heat receiver tube of a first embodiment;

(4) FIG. 3 shows cross sections of a heat receiver tube of a second embodiment; and

(5) FIG. 4 shows a cross section of a parabolic through collector (solar collector) with the heat receiver tube.

DETAILED DESCRIPTION

(6) Given is a heat receiver tube 1. The heat receiver tube 1 comprises a core tube 11 stainless steel. The core tube 11 comprises a core tube surface 112 with at least one solar energy absorptive coating for absorbing solar radiation 113 of the sunlight

(7) In the core tube 11 a heat transfer fluid 111 can be located. The heat transfer fluid 111 is a thermo-oil. Alternatively the heat transfer fluid 111 is molten salt.

(8) The enveloping tube 10 comprises an enveloping tube wall 101 out of glass. This enveloping tube wall is transparent for the solar radiation 113. The enveloping tube wall 101 comprises an inner enveloping tube surface 102, the external surface is coated by an AR layer (anti reflecting coating).

(9) The core tube 11 and the enveloping tube 10 are coaxially arranged to each other. The core tube surface 112 and the inner enveloping tube surface 102 arranged face to face. By this an inner heat receiver tube space 12 results which is bordered by the core tube surface 112 and the inner enveloping tube surface 102.

(10) The core tube and the enveloping tube are coaxially arranged to each other such that an inner heat receiver tube space is formed which is bordered by the core tube surface and the inner enveloping tube surface.

(11) The heat receiver tube comprises at least one pressure adapting device for adapting a space pressure of the inner heat receiver tube space and an environmental pressure of an environment of the heat receiver tube.

(12) First Embodiment: The pressure adapting device comprises an opening (hole) which is drilled into the bellows wall of bellows (FIG. 2). The opening comprises an opening dimension 401 of about 15 mm. The opening is covered by a particle filter 41. The particle filter is a ceramic particle filter. In an alternative embodiment, the particle filter is a metal filter.

(13) Second Embodiment: The pressure adapting device comprises an opening which is drilled into a skirt which covers (partly) the bellows and the enveloping glass tube (FIG. 3). Again, the opening is covered by a ceramic filter. Alternatively, the particle filter is a metal filter.

(14) The solar collector is used in a solar thermal power plant for converting solar energy into electrical energy. The heated heat transfer fluid is used to produce steam via a heat exchanger. The steam is driving a turbine, which is connected to a generator. The generator produces current.

(15) The heat receiver tube 1 is part of a solar collector (parabolic trough collector) 1000. The solar collector 1000 comprises at least one parabolic mirror 7 with a sunlight reflective surface 70. By the solar radiation reflecting surface 70 sunlight 2 is directed to the focal line 71 of the parabolic mirror 7. The concentrated sunlight is absorbed by the heat receiver tube 1 (FIG. 4).

(16) The heat receiver tube 1 is arranged on the side of the incoming direct sunlight radiation 2.

(17) The solar collector 1000 is used in a solar thermal power plant for converting solar energy into electrical energy. The heated heat transfer fluid is used to produce steam via a heat exchanger. The steam is driving a turbine, which is connected to a generator. The generator produces current (electric energy).

(18) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(19) It should be noted that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.