JP2014006018A - Metal pipe for sunlight heat collection pipe, vacuum pipe type sunlight heat collection pipe, and solar heat power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal pipe for a sunlight heat collection pipe, in which penetration of hydrogen is restricted.SOLUTION: A metal pipe 10 for a sunlight heat collection pipe includes a metal pipe 11 through which heat medium is flowed, a light selective absorption film 12 which is provided on an outer surface of the metal pipe 11 and which absorbs light of 400-900nm, and a glass lining layer 13 provided on an inner surface of the metal pipe 11.

Description

  The present invention relates to a metal tube for a solar heat collecting tube, a vacuum tube type solar heat collecting tube, and a solar thermal power generation apparatus using the same.

  Solar thermal power generation (CSP: Concentrating Solar Power), for example, condenses sunlight with a solar reflector made of a mirror or the like to generate heat, heats a liquid such as oil with this heat, and converts this heat into steam It is a power generation system that converts and rotates the steam turbine to generate power. The principle of power generation is basically the same as that of traditional thermal power generation, but it is an environmentally friendly power generation system that uses solar heat instead of fuel combustion for heat generation.

  Solar thermal power generation includes parabolic trough, linear Fresnel, dish, and tower systems. For example, the parabolic trough type has a raindrop-shaped curved mirror serving as a solar reflector, and a pipe-shaped solar heat collecting tube installed near the focal point of the curved mirror. This is a power generation system that collects light on a solar heat collecting tube, heats a liquid such as oil flowing in the solar heat collecting tube, and thereby generates electric power. Compared with a tower type solar thermal power generation, it is excellent in that it is easy to construct a large-scale facility because the solar reflector is easily arranged.

  The solar heat collecting tube has, for example, a metal tube in which a heat medium flows and a glass tube with a predetermined interval so as to cover the outside of the metal tube. An airtightly sealed region is formed between the metal tube and the glass tube. The sealed area is evacuated to reduce heat loss due to convection and conduction. The sealing region is provided with sealing portions made of fixing metal fittings or the like at both ends of the metal tube and the glass tube, and is fixed through a part for joining the glass made of Kovar metal or the like to the metal.

  Usually, the temperature of the heat medium flowing through the metal tube reaches about 400 ° C. When such a high temperature state is applied for a long time, decomposition of the heat medium may occur. In particular, when the heat medium is a compound containing hydrogen, hydrogen is generated by decomposition. Usually, since hydrogen permeates through the metal tube, when the generated hydrogen enters the sealed region between the metal tube and the glass tube, the degree of vacuum in the sealed region is lowered, and as a result, heat loss increases.

  Conventionally, various methods have been studied in order to suppress a decrease in the degree of vacuum due to the penetration of hydrogen into the sealing region and an increase in heat loss due to this. Specifically, a method for removing hydrogen that has entered the sealing region and a method for suppressing hydrogen from entering the sealing region have been studied. As a method of removing hydrogen, a method of arranging a getter substance in a sealing region or a method of providing a hydrogen pumping pump in the sealing region is known (for example, see Patent Document 1). Further, as a method for suppressing the permeation of hydrogen through a metal tube, a method of forming a chromium oxide coating on the inner surface of the metal tube by heat-treating the metal tube is known (for example, see Patent Document 2).

  It is also known to avoid an increase in heat loss by not forming a sealing region outside the metal tube. For example, there is one that omits the use of a glass tube by baking a glass powder on the outer surface of a metal tube to provide a glass lining layer containing ceramic particles (see Patent Document 3).

JP-A-64-79545 US Patent Application Publication No. 2007/0235023 JP 2011-158227 A

  With only the above-described method of arranging the getter material, it is difficult to extract hydrogen after long-term use. In addition, in the method of providing a hydrogen pump, it is necessary to provide a socket for fixing the thin film constituting the hydrogen pump on the glass tube, which requires a design change of the glass tube and the pumping of hydrogen. For this reason, heating of the thin film is required.

  Further, in the method of providing a chromium oxide coating on the inner surface of a metal tube, it is not always easy to form a chromium oxide coating with a uniform thickness, and fine holes such as pinholes are likely to occur. When fine pores are generated, hydrogen permeation may not be sufficiently suppressed. The chromium oxide coating is performed by heat-treating the metal tube. Since the length of the metal tube is about several meters, a large facility is required for the heat treatment.

  In the method of baking the glass powder and providing the glass lining layer containing ceramic particles, no glass tube is provided, so that a problem due to hydrogen intrusion into the sealing region does not occur. However, for example, when a glass lining layer is provided by baking glass powder on the outer surface of a metal tube in a case having a glass tube, it is not easy to form a glass lining layer having a uniform thickness, and fine holes such as pinholes are formed. Is likely to occur. In addition, cracking and peeling are likely to occur because the temperature cycle from room temperature to about 400 ° C. is repeated every day during operation. When fine holes, cracks, or peeling occurs, hydrogen permeation may not be sufficiently suppressed.

  This invention solves the said subject and aims at provision of the metal tube for solar heat collecting tubes which suppressed the penetration | invasion of the hydrogen to the sealing area | region in a solar heat collecting tube. Another object of the present invention is to provide a vacuum tube type solar heat collecting tube provided with a glass tube at a predetermined interval so as to cover the metal tube for the solar heat collecting tube of the present invention. It is another object of the present invention to provide a solar power generation apparatus using the vacuum tube type solar heat collecting tube of the present invention.

  The metal tube for solar heat collecting tubes of the present invention includes a metal tube for circulating a heat medium therein, a light selective absorption film for absorbing light of 400 to 900 nm provided on the outer surface of the metal tube, and the metal tube. And a glass lining layer provided on the inner surface.

  The vacuum tube type solar heat collecting tube of the present invention includes a metal tube for a solar heat collecting tube, a glass tube provided so as to surround the outside of the metal tube for the solar heat collecting tube, and the metal tube for the solar heat collecting tube. And a sealing portion that hermetically seals between the glass tube and the metal tube for solar heat collecting tube is the above-described metal tube for solar heat collecting tube of the present invention. Further, the solar thermal power generation apparatus of the present invention has a heat collector including a vacuum tube type solar heat collecting tube and a light collecting means for collecting sunlight, and the vacuum tube type solar heat collecting tube is the book described above. It is a vacuum tube type solar heat collecting tube of the invention.

  Since the metal lining for solar heat collecting tubes of the present invention is provided with a glass lining layer on the inner surface of the metal tube, hydrogen permeation from the metal tube can be suppressed. Thereby, when the metal tube for solar heat collecting tube of the present invention is used in a vacuum tube type solar heat collecting tube, the vacuum state of the sealed region between the metal tube and the glass tube can be maintained over a long period of time, Generation of heat loss can be suppressed.

Sectional drawing which shows one Embodiment of the metal tube for solar heat collecting tubes Process drawing which shows an example of the manufacturing method of the metal tube for solar heat collecting tubes. The partial sectional view showing one embodiment of a vacuum tube type solar heat collecting tube. The partial cross section figure which shows one Embodiment of the vacuum tube type solar heat collecting tube which has a junction part. The partial cross section figure which shows one Embodiment of the vacuum tube type solar heat collecting tube which has a protrusion part for welding. The partial cross section figure which shows one Embodiment of the vacuum tube type solar heat collecting tube which has a flange part. The external view which shows one Embodiment of the heat collector in a solar thermal power generation device. The top view which shows one Embodiment of a vacuum tube type solar heat collecting tube. AA line sectional view of the vacuum tube type solar heat collecting tube shown in FIG.

Embodiments of the present invention will be described below.
(Metal tubes for solar heat collecting tubes)
FIG. 1 is a cross-sectional view showing an embodiment of a metal tube for a solar heat collecting tube.
The metal tube 10 for solar heat collecting tubes includes a metal tube 11 that circulates a heat medium therein, a light selective absorption film 12 that is provided on the outer surface of the metal tube 11 and absorbs light of 400 to 900 nm, and a metal tube 11. And a glass lining layer 13 provided on the inner surface. The glass lining layer 13 may be in close contact with the inner surface of the metal tube 11 as a whole, and a part thereof may not be in close contact with the inner surface of the metal tube 11. In addition, the glass lining layer 13 is preferably partially bonded such as an end portion in order to improve adhesion.

  The glass lining layer 13 is suitable, for example, by softening a cylindrical glass member whose both ends are sealed by heating, and by inflating it with an expansion agent or the like filled therein so as to be in close contact with the inner surface of the metal tube 11. Formed. According to such a method, it is easy to form the glass lining layer 13 in which generation of pinholes and the like is suppressed, and hydrogen permeation from the pinholes and the like can be suppressed.

The glass lining layer 13 can be made of glass such as soda lime glass or borosilicate glass, and soda lime glass is particularly preferred. As soda lime glass, for example, SiO ₂ 71%, Al ₂ O ₃ 3%, Na ₂ O 16%, K ₂ O 2%, CaO 6%, and MgO 2% in oxide-based mass percentage display. What contains is mentioned as a preferable thing.

  The thickness of the glass lining layer 13 is not necessarily limited, but is preferably 0.1 mm or more. If the thickness is 0.1 mm or more, hydrogen permeation can be effectively suppressed, occurrence of pinholes and the like can be suppressed, and hydrogen permeation through pinholes and the like can be suppressed. The thickness is more preferably 0.3 mm or more, and further preferably 0.5 mm or more. The thickness is preferably 2 mm or less. If thickness is 2 mm or less, formation of the glass lining layer 13 demonstrated below can be made easy. Further, the thickness is more preferably 1.5 mm or less, and further preferably 1 mm or less.

The metal tube 11 is not necessarily limited as long as it is made of a metal material. From the viewpoint of suppressing damage to the glass lining layer 13 due to a difference in thermal expansion between the metal tube 11 and the glass lining layer 13, a metal material having a small difference in thermal expansion from the glass material constituting the glass lining layer 13 is preferable. Here, the thermal expansion coefficient (α) of soda lime glass suitably used for the glass lining layer 13 is, for example, 94 to 105 × 10 ⁻⁷ / ° C. Therefore, a metal material having a thermal expansion coefficient of 175 × 10 ⁻⁷ / ° C. or less is more preferable as the metal material. Specific examples of the metal material having such a thermal expansion coefficient include carbon steel (α = 110 to 120 × 10 ⁻⁷ / ° C.) and ferritic stainless steel (α = 110 to 120 × 10 ⁻⁷ / ° C.). ), Austenitic stainless steel (α = about 173 × 10 ⁻⁷ / ° C.) and the like.

  The light selective absorption film 12 preferably absorbs solar radiation energy, that is, absorbs light of 400 to 900 nm while reducing heat radiation to the outside, and a known light selective absorption film can be used. Examples of the light selective absorption film include a dielectric layer and one or more chromium-based layers selected from the group consisting of chromium, chromium nitride, and chromium oxynitride. Alternatively, those having a titanium silicon alloy layer, a titanium oxide layer, and a silicon oxide layer, and those having a cermet layer of molybdenum and silicon oxide can be given.

(Method of manufacturing metal pipe for solar heat collecting pipe)
Next, the manufacturing method of the metal tube 10 for solar heat collecting tubes is demonstrated.
FIG. 2 is a process diagram showing a method for manufacturing the metal tube 10 for solar heat collecting tubes, and in particular, a process diagram showing a method for forming the glass lining layer 13.

First, a cylindrical glass member having an outer diameter slightly smaller than the inner diameter of the metal tube 11, a wall thickness of 1 to 2 mm, and a length slightly longer than the metal tube 11 is prepared. . The cylindrical glass member is composed of, for example, SiO ₂ 71%, Al ₂ O ₃ 3%, Na ₂ O 16%, K ₂ O 2%, CaO 6%, MgO 2% in terms of mass percentage in terms of oxide. There is a soda lime glass having a thermal expansion coefficient of 95 × 10 ⁻⁷ / ° C. The cylindrical glass member is manufactured by a well-known method appropriate for the tube diameter such as the Danner method or the bellows method.

As shown in FIG. 2 (a), the cylindrical glass member 13 is sealed by heating and softening one end, and thermally expands inside, for example, KClO ₃ , NaClO ₄ , KNO ₃ , After selecting and filling one type selected from NHClO ₄ , NaNO ₃ , NH ₄ NO _3, etc., the other end is heated and softened and sealed.

  Thereafter, as shown in FIG. 2B, a metal lid portion 22 having a substantially hemispherical inner surface that covers the end portion of the cylindrical glass member 13 is fixed to one end portion of the metal tube 11, and the metal tube 11 One end of the is closed. The method for fixing the metal lid portion 22 to the metal tube 11 is not particularly limited. For example, although not shown, when a flange portion as will be described later is provided at the end of the metal tube 11, a similar flange portion is also provided in the metal lid portion 22, and mounting holes and the like provided in these are provided. The bolts and nuts may be used for fixing, and other fixing methods may be employed.

  After the one end is closed, the cylindrical glass member 13 whose both ends are sealed is inserted into the metal tube 11. After the insertion, another metal lid portion 22 is fixed to the other end portion of the metal tube 11 and the other end portion of the metal tube 11 is closed. The metal tube 11 having the metal lid portions 22 fixed to both ends in this manner is put into a firing furnace (not shown).

  And it heats to 600-700 degreeC with a predetermined | prescribed temperature increase rate, and this temperature state is hold | maintained for the predetermined time. When the whole is heated, the cylindrical glass member 13 is softened and the expansion agent 21 is thermally decomposed. The generated gas increases the internal pressure of the cylindrical glass member 13 and the cylindrical glass member 13 expands. Thereby, as shown in FIG.2 (c), the cylindrical glass member 13 is crimped | bonded to the inner surface of the metal tube 11, and the glass lining layer 13 is formed.

  After a predetermined holding time elapses, the metal tube 11 is kept in the firing furnace and slowly cooled at a predetermined temperature decrease rate. When the temperature drops to room temperature, the metal tube 11 is taken out from the firing furnace, and the metal lid portions 22 fixed to both ends are removed. Thereafter, the cylindrical glass member 13 protruding from both end portions of the metal tube 11 is cut out, and the cut surface of the cylindrical glass member 13 is flattened using a flat polishing machine such as a sand polishing rotary polishing plate (not shown) as necessary. To polish. After the formation of the glass lining layer 13, the light selective absorption film 12 is provided on the outer surface of the metal tube 11, whereby the solar heat collecting tube metal tube 10 is obtained.

(Vacuum tube type solar collector tube)
3 to 6 are partial cross-sectional views showing an example of an end portion of the vacuum tube type solar heat collecting tube 30 (hereinafter, abbreviated as the heat collecting tube 30) of the present invention. The right side of the partial cross-sectional view is the central part side in the axial direction of the metal tube 11 (hereinafter referred to as the axial center part side), and the left side of the metal tube 11 is the end part side in the axial direction (hereinafter referred to as the axial end part side). explain. In the present specification, one end of the metal tube 11 will be described, but the same can be applied to the other end.

  The heat collecting tube 30 includes a solar heat collecting tube metal tube 10, a glass tube 31 provided so as to surround the outside of the solar heat collecting tube metal tube 10, a solar heat collecting tube metal tube 10, and a glass tube 31. And a sealing portion 32 that hermetically seals the gap between the two. The sealing portion 32 connects, for example, the sealing protrusion 14 provided on the outer surface near the end of the metal tube 11, and the outer peripheral portion of the sealing protrusion 14 and the end of the glass tube 31. And a bellows 34.

  The sealing protrusion 14 is usually provided so as to make one round in the circumferential direction on the outer surface of the metal tube 11 and has a disk shape. The sealing protrusion 14 may be formed integrally with the metal tube 11 or may be joined to the metal tube 11 by welding or the like.

  The bellows 34 is provided to relieve a difference in axial thermal expansion between the metal tube 11 and the glass tube 31 and hermetically seal the sealing region 33 between the metal tube 11 and the glass tube 31. Yes. Thereby, even if the metal tube 11 expands during use for solar power generation, the sealed region between the metal tube 11 and the glass tube 31 can be kept airtight. The bellows 34 is provided so as to surround the metal tube 11. For example, one end is joined to the outer peripheral portion of the sealing projection 14 by welding or the like, and the other end is joined to the end of the glass tube 31. . The other end is joined to the end of the glass tube 31 by, for example, a glass / metal joint 35 made of Kovar metal or the like.

  The heat collecting tube 30 shown in FIG. 3 is suitably connected to the other heat collecting tube 30 by welding, for example, and includes a joint for joining the metal tube 11 and the glass lining layer 13 as described later, and the like. It does not have a welding projection or flange used for connection with the heat collecting tube 30.

Such things, the position P _G of the end of the glass lining layer 13 is either the same position as the position P ₁ of the end of the shaft center portion of the sealing projections 14, the shaft end side than this preferable. When the position P _G is closer to the shaft center than the position P _1, hydrogen easily passes through the gap between the sealing protrusion 14 and the glass lining layer 13, and the sealing between the metal tube 11 and the glass tube 31 is performed. There is a possibility that the vacuum state of the stop region 33 is lowered. By at least the position P _G and the position P ₁ and the same position, it is possible to suppress the deterioration of the vacuum in the seal region 33 to suppress permeation of hydrogen. Position P _G, from the viewpoint of suppressing a decrease in the vacuum of more effectively suppressed to seal region 33 of the permeation of hydrogen, and the position P ₂ of the end portion of the shaft end portion side of the sealing protrusion 14 The same position or the shaft end side is more preferable than this.

Further, the position P _G is preferably closer to the center of the shaft than the position P ₀ at the end of the metal tube 11. If Atsumarinetsukan 30 is connected by welding and other heat collection tube 30, the position P _G is at the same position as the position P _0, there is a possibility that the glass lining layer 13 from being damaged by a temperature during welding. The inventor conducted a welding test and confirmed that the thermal cracking of the glass lining layer extends to 10 mm from the weld. Therefore, from the viewpoint of suppressing damage to the glass lining layer 13, the position P _G is preferably away than 10mm from the position P ₀ in the axial central portion. On the other hand, the distance between the position P _G and the position P ₀ is preferably 40 mm or less. By setting it to 40 mm or less, the relationship between the position P _G and the position P ₁ or the position P ₂ can be improved.

Adjustment of the position P _G of the glass lining layer 13, for example, during the production of the solar collector tube metal tube 10 as described above, the glass lining layer 13 particularly to the inner surface of the metal tube 11 (the cylindrical glass member 13) the formation, on the inner surface of the metal tube 11 from the position P ₀ of the end of the pre-metal pipe 11 to a position P _G of the glass lining layer 13, the anti-fusing agent, such as to prevent fusion of the tubular glass member 13 It can be performed by coating and then inserting the cylindrical glass member 13 and performing heat treatment and slow cooling treatment, and then separating and removing the unfused portion.

  FIG. 4 is a partial cross-sectional view showing an example of an end portion of the heat collecting tube 30 having the joint 15 that joins the metal tube 11 and the glass lining layer 13. This heat collecting tube 30 also does not have a welding projection or flange portion used for connection with another heat collecting tube 30 as will be described later.

  The glass lining layer 13 only needs to be in close contact with the metal tube 11 and does not necessarily have to be joined to the metal tube 11. It is preferable to be bonded by the bonding portion 15, and it is particularly preferable that the end portion is bonded by the bonding portion 15. For example, the joint portion 15 is provided so as to make one round of the inner surface of the metal tube 11 in the circumferential direction. By providing such a joint portion 15, for example, hydrogen can be prevented from entering from the end of the glass lining layer 13 into a slight gap between the metal tube 11 and the glass lining layer 13. Permeation of hydrogen can be suppressed.

Position P ₄ of the end portion of the shaft end side of the joint portion 15, or the same position as the position P _1, which shaft end side is preferable than. When the position P ₄ is closer to the shaft center than the position P _1, hydrogen easily passes through the gap between the sealing protrusion 14 and the joint 15, and the sealing between the metal tube 11 and the glass tube 31 is performed. There is a possibility that the vacuum state of the region 33 is lowered. By at least the position P ₄ to the position P ₁ and the same position, it is possible to suppress the deterioration of the vacuum in the seal region 33 to suppress permeation of hydrogen. The position P ₄ is more preferably located closer to the position P ₂ than the position P ₂ from the viewpoint of suppressing hydrogen permeation more effectively and suppressing the decrease in the vacuum state of the sealing region 33. The position P ₃ of the end portion of the shaft center side of the joint portion 15 is not particularly limited.

In the case of providing a joint 15, the position P _G of the end of the glass lining layer 13 is not necessarily located P ₁ at the same position if this axial end portion than are joined by a joining portion 15 it may be a shaft center side than the position P ₁ to the extent. Preferably, the position is closer to the shaft end than the position P _1, and more preferably the position is closer to the position P ₂ and closer to the shaft end. In this case, the position of the joint 15 is preferably changed appropriately in accordance with the position P _G.

  The length of the bonded portion (the length in the axial direction of the metal tube 11) that is the portion actually bonded to the glass lining layer 13 in the bonded portion 15 is preferably 1 mm or more. By setting the length of the joined portion to 1 mm or more, hydrogen can be effectively prevented from entering the slight gap between the glass lining layer 13 and the metal tube 11, and hydrogen can be prevented from entering the sealing region 33. Can be suppressed. As for the length of a junction part, 3 mm or more is more preferable. Further, the length of the joining portion is sufficient if it is 30 mm in order to suppress the intrusion of hydrogen, and the productivity of the heat collecting tube 30 can be improved by setting it to be less than this.

Position _{P 4,} the shaft center side is preferable than the position _{P 0.} If Atsumarinetsukan 30 is connected by welding and other heat collection tube 30, the position P ₄ is at the same position as the position P _0, the junction 15 by temperature during welding may be damaged. From the viewpoint of suppressing damage to the joint 15 as described above, the position P ₄ is preferably separated from the position P ₀ by 10 mm or more toward the shaft center. On the other hand, the interval between the position _{P 4} and the position _{P 0} is preferably 40mm or less. By setting it to 40 mm or less, the relationship between the position P ₄ and the position P ₁ or the position P ₂ can be improved.

  The constituent material of the joining part 15 is not necessarily limited as long as it can effectively join the metal tube 11 and the glass lining layer 13. For example, a low melting glass material is preferable, and a low melting glass material having a softening temperature of 450 to 650 ° C. or lower is more preferable.

  Such a joint 15 can be formed, for example, at the time of manufacturing the metal tube 10 for solar heat collecting tubes as described above, particularly at the time of forming the glass lining layer 13 on the inner surface of the metal tube 11. For example, it can be formed by previously applying a low-melting glass material to a portion of the inner surface of the metal tube 11 where the joint 15 is provided, and then inserting the glass lining layer 13 and heat-treating it.

  FIG. 5 is a partial cross-sectional view showing an example of an end portion of the heat collecting tube 30 provided with a welding protrusion 16 for connection to another heat collecting tube 30 by welding.

  When connecting with the other heat collection pipe | tube 30 by welding, it is preferable to provide the protrusion part 16 for welding so that it may protrude in the outer surface of the edge part of the metal pipe 11. FIG. The welding protrusion 16 is provided, for example, so as to make one round in the circumferential direction on the outer surface of the end of the metal tube 11 and has a disk shape. By providing such a welding protrusion 16, the substantial distance between the welded portion and the end of the glass lining layer 13 can be extended, and the influence of welding can be effectively suppressed. In addition, welding is performed with respect to the outer peripheral part vicinity of these one pair of welding protrusions 16, for example in the state which faced the welding protrusion 16 and the welding protrusion 16 of the other heat collecting tube 30. FIG.

  The height of the welding projection 16, that is, the height from the outer surface of the metal tube 11 to the outer peripheral portion of the welding projection 16 is preferably 20 mm or more. By setting it as such height, the distance of a welding part and the edge part of the glass lining layer 13 can be ensured effectively, and the influence by welding can be suppressed. A height of 50 mm is sufficient for suppressing the influence of welding, and heat dissipation loss due to an increase in the heat dissipation area can be suppressed by setting the height below this height.

  As for the thickness of the protrusion part 16 for welding, ie, the length in the axial direction of the metal pipe 11, 5 mm or more is preferable. By setting it as such thickness, while being able to suppress the influence by welding more effectively, the mechanical strength of a welding part etc. can also be made favorable. A thickness of 10 mm is sufficient for suppressing the influence of welding, and heat dissipation loss due to an increase in the heat dissipation area can be suppressed by setting the thickness to less than this.

By providing the welding protrusion 16, the influence of welding on the glass lining layer 13 can be suppressed. Therefore, the position P _G need not be a shaft center side than necessarily position P _0, can also at the same position as the position P _0. Even provided welding protrusions 16, positional relationship between the position P _G of the glass lining layer 13 relative to the position P ₁ and the location P ₂ of the sealing protrusions 14, and the case without the weld protrusions 16 The same is preferable.

Moreover, although not shown in figure, the junction part 15 may be provided. In this case, since it is possible to suppress the influence of welding to the joint 15 by welding protrusions 16, the position P ₄ need not be a shaft center side than necessarily position P _0, in the same position as the position P ₀ it can. The positional relationship between the position P ₄ with respect to the position P ₁ and the location P ₂ are preferably the same as the case without the weld protrusions 16.

  FIG. 6 is a partially enlarged cross-sectional view showing an example of an end portion of the heat collecting tube 30 having the flange portion 17 for connecting to another heat collecting tube 30 without welding.

  When connecting to another heat collecting tube 30 without welding, it is preferable to provide a flange portion 17 that can be fixed without welding so as to protrude from the outer surface of the end portion of the metal tube 11. The flange portion 17 is provided so as to make one round in the circumferential direction on the outer surface of the end portion of the metal tube 11, for example, and has a disk shape. Moreover, the flange part 17 has the attachment hole 171 for attaching with the flange part 17 of the other heat collecting tube 30, for example with a volt | bolt or a nut. The connection by the flange portion 17 is performed by, for example, abutting the flange portion 17 and the flange portion 17 of another heat collecting tube 30 through a gasket and fixing them with bolts or nuts using the mounting holes 171 of both. . According to such a flange part 17, since it is not necessary to weld, damage to the edge part of the glass lining layer 13 can be suppressed.

In the case of providing a flange portion 17, it is not necessary to perform the welding, the position P _G need not be a shaft center side than necessarily position P _0, it is also possible to position P ₀ at the same position.

Moreover, although not shown in figure, the junction part 15 may be provided. In this case, it is not necessary to perform the welding, the position P ₄ need not be a shaft center side than necessarily position P _0, can be at the same position as the position P _0. Even when providing the flange portion 17, positional relationship between the position _{P 4} of the _{P G} and the junction 15 of the glass lining layer 13 relative to the position _{P 1} and the location _{P 2} of the sealing protrusion 14 is provided with a flange portion 17 The same as the case where there is no is preferable.

(Solar thermal power generator)
FIG. 7 is an external view of a parabolic trough heat collector as an embodiment of the heat collector in the solar thermal power generation apparatus.

  The parabolic trough heat collector 40 includes a parabolic reflector 41 that is a parabolic reflector as a light collecting means. The parabolic reflector 41 is supported by a reflector support 42. The heat collecting tube 30 of the embodiment is provided at the focal portion of the parabolic reflector 41 so as to extend along the focal portion. The heat collecting tube 30 is fixed to the parabolic reflecting mirror 41 and the reflecting mirror support 42 by a heat collecting tube support 43.

  In such a parabolic trough heat collector 40, sunlight is condensed on the heat collecting tube 30 by the parabolic reflecting mirror 41, and the heat collecting tube 30 is heated by the condensed sunlight. A heat medium such as oil flows inside the heat collection tube 30, and the internal heat medium is heated by heating the heat collection tube 30. Although not shown, the parabolic trough heat collector 40 is connected to a steam turbine, and power is generated by rotating the steam turbine using the heat of the heat medium.

  FIG. 8 is a plan view showing an embodiment of the heat collecting tube 30. FIG. 9 is a cross-sectional view of the heat collection tube 30 shown in FIG.

The heat collecting tube 30 includes a metal tube 11 made of a metal tube through which a heat medium flows, a light selective absorption film 12 is provided on the outer surface, and a glass lining layer 13 is provided on the inner surface. In addition, a glass tube 31 is provided outside the metal tube 11 at a predetermined interval so as to cover the metal tube 11. The metal tube 11 and the glass tube 31 are fixed with sealing portions 32 provided at both ends so that a hermetically sealed region 33 is formed between them. The sealing region 33 is normally in a vacuum state, for example, 1 × 10 ⁻³ Pa or less.

DESCRIPTION OF SYMBOLS 10 ... Metal tube for solar heat collecting tubes, 11 ... Metal tube, 12 ... Light selective absorption film, 13 ... Glass lining layer, 14 ... Projection part for sealing, 15 ... Joint part, 16 ... Projection part for welding, 17 ... Flange part, 171 ... mounting hole, 21 ... expansion agent, 22 ... metal lid part, 30 ... vacuum tube type solar heat collecting tube, 31 ... glass tube, 32 ... sealing part, 33 ... sealing region, 34 ... bellows, 40 ... Parabolic trough collector, 41 ... Parabolic reflector, 42 ... Reflector support, 43 ... Heat collector support, P ₀ ... Position of the end of the metal tube, P ₁ ... The position of the end on the shaft center side, P ₂ ... The position of the end on the shaft end side of the sealing projection, P ₃ ... The position of the end on the shaft center side of the joint, P ₄ ... The joint The position of the end on the shaft end side, P _G ... The position of the end of the glass lining layer

Claims (12)

A metal tube that circulates the heat medium inside,
A light selective absorption film that absorbs light of 400 to 900 nm provided on the outer surface of the metal tube;
A metal tube for a solar heat collecting tube, comprising: a glass lining layer provided on an inner surface of the metal tube.   The said glass lining layer is a metal tube for solar heat collecting tubes of Claim 1 which consists of a cylindrical glass member.   The metal tube for solar heat collecting tubes according to claim 1 or 2, wherein the glass lining layer has a thickness of 0.1 to 2 mm. The metal tube for solar heat collecting tubes according to any one of claims 1 to 3,
A glass tube provided so as to surround the outside of the metal tube for solar heat collecting tube;
A vacuum tube type solar heat collecting tube having a sealing part for hermetically sealing the metal tube for the solar heat collecting tube and the glass tube.   The vacuum tube type solar heat collecting tube of Claim 4 which has the protrusion part for sealing which comprises a part of said sealing part in the outer surface of the said metal tube. When the central portion side in the axial direction of the metal tube is the axial central portion side, and the end portion side in the axial direction of the metal tube is the axial end portion side,
The end of the glass lining layer is
The end of the sealing projecting portion on the side of the central portion of the shaft is placed on the same side, more on the side of the shaft end than this,
The vacuum tube type solar heat collecting tube according to claim 5, wherein the vacuum tube type solar heat collecting tube is located closer to the shaft center than the end of the metal tube.   The vacuum tube type solar heat collecting tube of any one of Claims 4-6 which has a junction part which joins the said metal tube and the said glass lining layer in the circumferential direction. The end on the shaft end side of the joint is
The end of the sealing projecting portion on the side of the central portion of the shaft is placed on the same side, more on the side of the shaft end than this,
The vacuum tube type solar heat collecting tube according to claim 7, wherein the vacuum tube type solar heat collecting tube is located closer to an axial center portion than an end portion of the metal tube.   The vacuum tube type solar heat collecting tube according to claim 7 or 8, wherein the bonding is performed by bonding ends of the glass lining layer.   The vacuum tube type solar heat collecting tube of any one of Claims 4-9 which has a protrusion part for welding utilized for the connection by welding with another metal pipe in the outer surface of the edge part of the said metal pipe.   The vacuum tube type solar heat collecting tube according to any one of claims 4 to 9, wherein the metal tube has a flange portion used for connection not by welding with another metal tube on an outer surface of an end portion. A solar thermal power generation apparatus having a heat collector comprising a vacuum tube type solar heat collecting tube and a light collecting means for collecting sunlight on the vacuum tube type solar heat collecting tube,
The said solar tube type solar heat collecting tube is a vacuum tube type solar heat collecting tube of any one of Claims 4-11, The solar thermal power generation apparatus characterized by the above-mentioned.

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