CN108413617B - High-temperature vacuum tube bundle heat absorber of small tower system - Google Patents
High-temperature vacuum tube bundle heat absorber of small tower system Download PDFInfo
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- CN108413617B CN108413617B CN201810145273.3A CN201810145273A CN108413617B CN 108413617 B CN108413617 B CN 108413617B CN 201810145273 A CN201810145273 A CN 201810145273A CN 108413617 B CN108413617 B CN 108413617B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/44—Heat exchange systems
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/47—Mountings or tracking
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Abstract
The invention discloses a high-temperature vacuum tube bundle heat absorber of a small tower system, which comprises: a plurality of vacuum heat absorption pipes with oval or round middle belly cross sections, wherein the number of pipe rows adopts double rows of regular triangle pipes; the vacuum heat absorption tube comprises an inner metal flat tube or round tube and an outer glass tube, and the inner metal flat tube or round tube and the outer glass tube are connected through an expansion joint; the front row of inlet metal tubes and the rear row of outlet metal tubes are connected through a top corrugated tube at the upper part of the tube bundle; at the lower part of the tube bundle, the metal tube at the rear discharge inlet is connected with the flow divider, and the metal tube at the front discharge outlet is connected with the current collector; the exposed inner pipe and the corrugated pipe are coated with heat insulating materials, and the heat absorber is fixed on the heat absorbing tower through the part near the inlet and the outlet of the inner pipe. The solar heliostat has strong capacity of absorbing reflected light and small heat loss, and can receive light energy converged by heliostats from different areas in different time periods.
Description
Technical Field
The invention relates to the technical field of solar energy utilization, in particular to a high-temperature vacuum tube bundle heat absorber of a small tower system.
Background
In the whole tower type solar thermal power generation system, the heat absorber is the key for realizing the photo-thermal conversion. The heat absorber receives solar radiation energy projected by the heliostat and converts the solar radiation energy into heat energy of the working medium. The heat absorber is required to have the characteristics of small volume, high energy conversion efficiency and the like. The selection, the size and the structure of the heat absorber are all related to the number of the heliostats, the arrangement of the heliostats, the types of working media, the required outlet parameters of the heat absorber and other factors.
The tower type heat absorber can be roughly divided into the following types: the heat absorber comprises a cavity type heat absorber, an external heat absorber, a flat plate type heat absorber, a fluidized bed heat absorber and the like, but the existing practical application of the current mainstream comprises only the cavity type heat absorber and the external heat absorber, and the two heat absorbers respectively have advantages and disadvantages. The opening of the cavity type heat absorber is small, the heat loss is small, but the mirror field layout is limited by the smaller size of the cavity opening; the external heat absorber can receive reflected light in the 360-degree direction, so that the overall layout of the heliostat field is more reasonable and the heliostat field is suitable for a large-capacity system, but the heat absorber is completely exposed in the environment, and the heat exchange with the outside is particularly large, so that the heat loss is large, and the heat efficiency is relatively low.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a high-temperature vacuum tube bundle heat absorber of a small tower system, which has strong capability of absorbing reflected light and small heat loss, and can receive light energy converged by heliostats from different areas in different time periods.
In order to solve the above technical problem, the present invention provides a high temperature vacuum tube bundle heat absorber of a small tower system, comprising: a plurality of vacuum heat absorption pipes with oval or round middle belly cross sections, wherein the number of pipe rows adopts double rows of regular triangle pipes; the vacuum heat absorption tube comprises an inner metal flat tube or a thick round tube 5 and an outer glass tube 4, and the inner metal flat tube or the thick round tube 5 is connected with the outer glass tube 4 through an expansion joint; at the upper part of the tube bundle, the front row inlet metal tubes 8 and the rear row outlet metal tubes 6 are connected through the top bellows 7; in the lower part of the tube bundle, the rear discharge inlet metal tube 3 is connected with the flow divider 2, and the front discharge outlet metal tube 9 is connected with the current collector 10; the exposed inner pipe and the corrugated pipe are coated with heat insulating materials, and the heat absorber is fixed on the heat absorbing tower through the part near the inlet and the outlet of the inner pipe.
Preferably, the size of the cross section of the outer tube of the vacuum heat absorption tube is 20-200 mm.
Preferably, the vacuum heat absorption pipes are connected in series, in parallel or in series and parallel, and are arranged horizontally or vertically in the heat absorption surface.
Preferably, the side of the inner tube facing the mirror field is provided with a selective absorption coating, and the side facing away from the mirror field is provided with a plurality of non-evaporable getters.
Preferably, the inner tube is provided with short fins on both sides of the major axis direction of the ellipse or both sides of the diameter of the circle, and the distance between the fin tips and the inner side of the glass outer tube is 2mm at the shortest distance.
Preferably, the cross section of the middle belly of the vacuum heat absorption pipe is an ellipse or a thick circle, and the two ends of the vacuum heat absorption pipe are transited to a thin circle.
Preferably, the side surfaces and the back surfaces of the arranged vacuum tube bundles are provided with insulating layers, and the inner surfaces of the insulating layers are coated with reflecting coatings.
Preferably, the heat sink is rotated as a whole about a vertical axis.
Preferably, the top of the heat absorption tower is provided with a corresponding counterweight.
The invention has the beneficial effects that: (1) the primary light leakage rate is reduced, and the primary light leakage rate is greatly reduced by arranging the double-row pipes and flattening the circular pipe into the elliptical pipe; (2) the front and rear calandria are connected with each other through a corrugated pipe at the upper part of the tube bundle; at the lower part of the tube bundle, the round inner tube at the inlet is connected with the flow divider, and the metal tube at the outlet is connected with the flow collector; when the metal pipe is expanded by heat, the elongation in the axial direction can be compensated by compressing the flexible corrugated pipe, thereby reducing the stress of the pipe-to-pipe connection part caused by the relative linear expansion difference due to uneven heating; (3) the rotating mechanism at the bottom of the heat absorber can realize time-sharing condensation, is suitable for a multi-tower condensation system adopting a time-sharing condensation scheme, can receive light energy converged by heliostats from different regions in different time periods, and has obviously improved cosine efficiency compared with a conventional groove type condensation system matched with a vacuum tube heat absorber; (4) the fluid in the pipe is heated more uniformly, and the condition that the temperature of the fluid at the pipe wall is higher than that of the pipe core is improved; (5) the invalid heat absorption lengths at the two ends of the tube do not participate in heat absorption, so that the solar radiation is completely converged on the effective heat absorption section, and the energy loss of the solar radiation converged on the invalid heat absorption section is avoided; (6) the high-temperature metal inner pipes at the two ends of the glass pipe are close to each other, so that the temperature is higher, and the outer pipe section with higher temperature is applied with enough heat preservation, so that the heat loss of the whole heat absorber can be further reduced; (7) the theoretical limit of the geometric light-gathering ratio of the trough light-gathering system which is conventionally matched with a vacuum tube heat absorber is just over 100 times, but if the vacuum tube is combined into the planar heat absorber shown by the invention, the geometric light-gathering ratio can reach hundreds of times, and the heat loss distributed to a unit light-gathering mirror surface at the same working temperature is lower.
Drawings
Fig. 1(a) is a left side view of the overall structure of the heat absorber of the present invention.
Fig. 1(b) is a front view of the overall structure of the heat absorber of the present invention.
FIG. 2 is a schematic view of the mirror field of the present invention.
fig. 3 is a schematic view of the tower top heat absorber and counterweight of the present invention.
Fig. 4 is a schematic view of the arrangement of the vacuum bushing of the present invention.
Fig. 5 is an overall schematic view of the oval flat tube of the present invention.
FIG. 6 is a schematic view of the present invention at different angles of incidence.
FIG. 7 is a graph showing the light leakage rate curves of the elliptical tube and the circular tube with different angles according to the present invention.
wherein, 1, a cold working fluid inlet; 2. a flow divider; 3. then discharging the metal pipe into an inlet; 4. a glass tube; 5. a metal flat tube or a thick round tube; 6. a rear outlet metal tube; 7. a top bellows; 8. a front row of inlet metal tubes; 9. a front discharge outlet metal tube; 10. a current collector; 11. a hot working fluid outlet; 12. balancing weight; 13. a rotation mechanism; 14. a motor; 15. a heat sink; 16. a tower column; 17. a mirror field.
Detailed Description
As shown in fig. 1(a) and 1(b), a high-temperature vacuum tube bundle heat absorber of a small tower system comprises: a plurality of vacuum heat absorption pipes with oval or round middle belly cross sections, wherein the number of pipe rows adopts double rows of regular triangle pipes; the vacuum heat absorption tube comprises an inner metal flat tube or a thick round tube 5 and an outer glass tube 4, and the inner metal flat tube or the thick round tube 5 is connected with the outer glass tube 4 through an expansion joint; at the upper part of the tube bundle, the front row inlet metal tubes 8 and the rear row outlet metal tubes 6 are connected through the top bellows 7; in the lower part of the tube bundle, the rear discharge inlet metal tube 3 is connected with the flow divider 2, and the front discharge outlet metal tube 9 is connected with the current collector 10; the exposed inner pipe and the corrugated pipe are coated with heat insulating materials, and the heat absorber is fixed on the heat absorbing tower through the part near the inlet and the outlet of the inner pipe.
The shape of the tube of the invention adopts an elliptical tube or a circular tube, the size can be any, the range is changed within 20-200 mm, and the tube diameter can be adjusted according to the scale of a mirror field and the heat absorption capacity of a working medium. The number of the tube rows adopts double rows of regular triangle tubes, and the front and rear tube bundles are connected in series through flexible corrugated tubes without limiting axial extension. The front and rear calandria are connected with each other through a corrugated pipe at the upper part of the tube bundle; at the lower part of the tube bundle, the metal tubes at the inlet are connected with the flow divider, and the metal tubes at the outlet are connected with the flow collector. In order to reduce the heat loss of convection and radiation, the exposed inner pipe is coated with a heat-insulating material. The whole heat absorber can rotate around a vertical shaft, and time-sharing condensation is realized. The heat absorber is fixed on the heat absorbing tower through the inlet and outlet parts of the inner pipe. And a corresponding balance weight is arranged at the top of the heat absorption tower to balance the mass of the heat absorber. The side and the back of the arranged vacuum tube bundles are provided with heat-insulating layers, and the inner surfaces of the heat-insulating layers are coated with reflective coatings, so that light leakage can be reflected to the inner tube again. The heat absorption surface formed by the tube bundles has a certain inclination angle according to the scale size of the mirror field, solar radiation energy in the mirror field is reflected to the inner tube through the heliostat, the working medium in the tube is heated, and the solar energy is converted into heat energy of the working medium.
The side of the elliptical or circular inner tube, which faces away from the mirror field, is provided with a large number of getter, and the advantage is that the high vacuum maintaining time in the tube is prolonged.
two sides (not front and back sides) of the oval or round inner tube, namely two sides of the major axis direction of the oval or the diameter of the circle, can be provided with short fins, so that the gap between two adjacent tubes is further reduced, the primary light leakage rate is reduced, but the fins cannot touch the glass outer tube, and the distance between the tips of the fins and the inner side of the glass outer tube can be up to 2 mm.
In this example, the specification of the unit mirror field is 100m × 40m, and according to the tower height of 32m and the mirror height of 2m, the east-west length of a single mirror field module is 100m, the north-south length is 80m, and the distance between the nearest row of heliostats and the north-south of the tower is 15m, then the farthest heliostat is 140m away from the tower, as shown in fig. 2. The azimuth angle of the heat absorption surface is +/-139 degrees, so that the included angle between the connecting line of the centers of the heliostats in the closest row and the center of the heat absorption surface and a vertical line is 27 degrees, the included angle in the farthest row is 78 degrees, namely the altitude angle opening angle of the center of the heat absorption surface facing the heliostats in the closest and farthest rows is 78-27 degrees to 51 degrees, the maximum incidence angle in the altitude direction is 25.5 degrees, and the included angle between the heat absorption surface and the ground is 52.5 degrees. The included angle between the connecting line of the center of the heat absorption surface and the center of the most southeast (or the most southwest) heliostat and the east-west axis is 8.5 degrees, so that the azimuth opening angle of the heat absorption tower facing the mirror field is 81.5 degrees, and the maximum incident angle is 40.8 degrees. Therefore, the heat absorbing pipe should be placed obliquely downwards, and the cylindrical feature of the heat absorbing pipe is suitable for a larger azimuth opening angle, as shown in fig. 3.
When the tubes are arranged, the diameter of the outer tube is 90mm, the diameter of the inner tube is 40mm, the distance between the outer tubes in the same row is 5mm, namely the distance between the circle center and the circle center is 5+45+45 mm which is 95mm, two rows of tubes are arranged, and then the double rows of tubes are arranged in a triangular arrangement mode, as shown in fig. 4 and 5. Considering that a circular tube has a large primary light leakage rate in the actual working process, the circular inner tube is flattened into an elliptical tube, the length of the long half axis is 30mm, and the length of the short half axis is 5mm according to the equal circumference.
The angle of incidence is defined herein as the angle of the light ray to the normal plane to the plane of the tube row as shown in figure 6. Through the analysis of light leak rate, the light leak rate can have great change through different angle incidences:
(1) 0-9 degrees of incidence and 0 light leakage rate;
(2) the light leakage rate is gradually increased when the light is incident at 9-30 degrees, and the light leakage rate is 0.35 when the light is incident at 30 degrees;
(3) The light leakage rate is gradually reduced when the light is incident at 30-45 degrees, and the light leakage rate is 0 when the light is incident at 43 degrees;
(4) Incidence at 45-53 degrees and light leakage rate of 0;
(5) The light leakage rate is gradually increased when the light is incident at 53-60 degrees, and the light leakage rate is 0.33 when the light is incident at 60 degrees;
(6) The light leakage rate is gradually reduced when the light is incident at 60-65 degrees, and the light leakage rate is 0 when the light is incident at 65 degrees.
Fig. 7 is a light leakage rate curve when the heat absorption tubes are circular tubes and elliptical tubes, and it can be seen from the graph that when the incident angle of sunlight is changed within the range of 0 to 48 °, the primary light leakage rate is reduced by 0 to 21% in different incident angles, and therefore, the elliptical tubes are superior to the circular tubes in terms of light leakage rate. And because the reflective coating is arranged behind the tube row, a small amount of leaked light can be reflected to the tube for absorption, and almost all sunlight reflected by the mirror field is absorbed by the vacuum tube.
The working process of the heat absorber: the working medium firstly enters the flow divider, enters each rear-row pipe from the flow divider to absorb heat, then enters the front-row pipe through the flexible corrugated pipe at the upper part to fully absorb heat, and enters the current collector after reaching the specified temperature by controlling the flow rate to flow to the next part.
The heat absorber provided by the invention has strong capability of absorbing reflected light and small heat loss, and can receive light energy converged by heliostats from different areas in different time periods.
Claims (6)
1. The utility model provides a high temperature vacuum tube bank heat absorber of small-size tower system which characterized in that includes: a plurality of vacuum heat absorption pipes with oval or round middle belly cross sections, wherein the number of pipe rows adopts double rows of regular triangle pipes; the vacuum heat absorption pipe comprises an inner metal flat pipe or a thick round pipe (5) and an outer glass pipe (4), and the inner metal flat pipe or the thick round pipe (5) is connected with the outer glass pipe (4) through an expansion joint; the front row of inlet metal tubes (8) and the rear row of outlet metal tubes (6) are connected through a top corrugated tube (7) at the upper part of the tube bundle; at the lower part of the tube bundle, the rear discharge inlet metal tube (3) is connected with the flow divider (2), and the front discharge outlet metal tube (9) is connected with the current collector (10); the exposed inner pipe and the corrugated pipe are coated with heat insulation materials, and the heat absorber is fixed on the heat absorption tower through the part near the inlet and the outlet of the inner pipe; the side of the inner tube facing the mirror field is provided with a selective absorption coating, and the side of the inner tube facing away from the mirror field is provided with a large number of non-evaporable getters; the cross section of the middle belly of the vacuum heat absorption pipe is an ellipse or a thick circle, and two ends of the vacuum heat absorption pipe are transited to thin circles; the absorber is rotated as a whole about a vertical axis.
2. A high-temperature vacuum tube bundle heat absorber of a small tower system according to claim 1, wherein the size of the cross section of the outer tube of the vacuum heat absorbing tube is 20-200 mm.
3. A high temperature vacuum tube bundle heat absorber of a small tower system according to claim 1, wherein the vacuum heat absorbing tubes are connected in series, in parallel or in series and parallel, and are arranged horizontally or vertically in the heat absorbing surface.
4. A high temperature vacuum tube bundle heat absorber of a small tower system as claimed in claim 1, wherein the inner tube is provided with short fins on both sides in the major axis direction of the ellipse or on both sides in the diameter of the circle, and the distance between the tips of the fins and the inner side of the glass outer tube is 2mm at the nearest.
5. A high temperature vacuum tube bundle heat sink for a compact tower system according to claim 1 wherein the banks of vacuum tubes are arranged with insulation on the sides and back, the insulation having reflective coatings on the inside surface.
6. A high temperature vacuum tube bundle heat sink for a compact tower system as recited in claim 1 wherein the top of the heat sink tower is provided with a corresponding counterweight.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810145273.3A CN108413617B (en) | 2018-02-12 | 2018-02-12 | High-temperature vacuum tube bundle heat absorber of small tower system |
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| CN201810145273.3A CN108413617B (en) | 2018-02-12 | 2018-02-12 | High-temperature vacuum tube bundle heat absorber of small tower system |
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| CN108413617B true CN108413617B (en) | 2019-12-10 |
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| CN110849736B (en) * | 2019-12-17 | 2024-08-27 | 南京开关厂有限公司 | Pressure testing tool and application method thereof |
| CN112240655A (en) * | 2020-09-27 | 2021-01-19 | 深圳市德佳外贸有限公司 | Heat exchanger capable of automatically defrosting or deicing |
| CN112113453A (en) * | 2020-09-27 | 2020-12-22 | 深圳市德佳外贸有限公司 | Heat exchanger and heat exchanger system |
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| CN2431532Y (en) * | 2000-07-20 | 2001-05-23 | 陈大民 | Solar heat power unit |
| CN104896769B (en) * | 2015-06-10 | 2017-08-15 | 河海大学常州校区 | A kind of tower type solar chimney salt, water, cogeneration system and its operation method |
| CN107388596A (en) * | 2017-08-29 | 2017-11-24 | 中机华信诚电力工程有限公司 | A kind of tower surface heat dump tube panel of vacuum heat-preserving |
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