CN113494780B - Heat preservation device and heat preservation method for solar tower type heat absorber - Google Patents

Heat preservation device and heat preservation method for solar tower type heat absorber Download PDF

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Publication number
CN113494780B
CN113494780B CN202010196096.9A CN202010196096A CN113494780B CN 113494780 B CN113494780 B CN 113494780B CN 202010196096 A CN202010196096 A CN 202010196096A CN 113494780 B CN113494780 B CN 113494780B
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heat
heat storage
storage unit
temperature
absorber
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CN113494780A (en
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肖刚
曾季川
彭记康
徐有杰
倪明江
岑可法
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Zhejiang University ZJU
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Zhejiang University ZJU
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H7/00—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release
    • F24H7/02—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00—Details
    • F24H9/18—Arrangement or mounting of grates or heating means
    • F24H9/1854—Arrangement or mounting of grates or heating means for air heaters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S50/00—Arrangements for controlling solar heat collectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S60/00—Arrangements for storing heat collected by solar heat collectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S70/00—Details of absorbing elements
    • F24S70/60—Details of absorbing elements characterised by the structure or construction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D20/003—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using thermochemical reactions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S70/00—Details of absorbing elements
    • F24S70/60—Details of absorbing elements characterised by the structure or construction
    • F24S2070/62—Heat traps
    • 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
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/14—Thermal energy storage
    • 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
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

Abstract

The invention relates to the technical field of solar thermal power generation, and discloses a thermal insulation device and a thermal insulation method for a solar tower type heat absorber. The periphery of collection case under the heat-retaining unit is located, including porous metal and the chemical heat-retaining material as the frame body of heat-retaining unit, exhaust duct utilizes the hood to discharge gas. According to the heat preservation device and the heat preservation method for the solar tower type heat absorber, solar energy is stored in an internal energy form through a reduction reaction of a chemical heat storage substance at the initial stage of preheating, after a heliostat field is focused, the stored energy is released into heating gas through an oxidation reaction by the chemical heat storage substance, the heated gas enters an exhaust pipeline and is exhausted outwards through an air cap, and the lower end of a heat absorption pipe is heated by blowing so as to keep the temperature balance of the whole heat absorption pipe.

Description

Heat preservation device and heat preservation method for solar tower type heat absorber
Technical Field
The invention relates to the technical field of solar thermal power generation, in particular to a heat preservation device and a heat preservation method for a solar tower type heat absorber.
Background
Solar energy is the most abundant, clean and widely available renewable energy in the world, and the solar power generation technology is an effective means for relieving the energy crisis, so that the application prospect is wide. According to the difference of solar heat collection modes, the solar power generation technology is mainly divided into photo-thermal power generation and photovoltaic power generation, and the photo-thermal power generation technology applied in the current engineering practice can be divided into four types, namely a groove type solar power generation system, a linear Fresnel type power generation system, a tower type solar power generation system and a disc type solar power generation system. The tower type photo-thermal power generation system has the advantages of large capacity, high light concentration ratio and operation temperature, high photo-thermal conversion efficiency, high economic benefit and the like, and is one of the most rapidly developed photo-thermal power generation technologies at present.
The tower type solar power station utilizes a plurality of heliostats to reflect sunlight to a heat absorber at the top of a heat absorption tower and heat a heat transfer medium in a heat absorption pipe, so that the aims of condensing light and converting the light into heat energy of the heat transfer medium are fulfilled. The heat absorber on the top of the heat absorption tower belongs to the core equipment in the tower type solar power generation system, and generally comprises a heat absorption pipe, an upper header, a lower header and the like. After absorbing the radiation energy of sunlight, the working medium circulating in the heat absorption pipe is mixed in the upper header or the lower header and then enters the next pipe panel to continuously absorb heat or flow out of the heat absorber.
In order to prevent the focused sunlight from directly irradiating the upper and lower headers and the pipelines inside the heat absorber, a bulky insulation box and protective bricks are usually arranged around the upper and lower headers of the heat absorber. Due to the shielding of the heat insulation box with large volume, the lower area of the light receiving surface of the heat absorber cannot be irradiated by sunlight reflected by a heliostat field during preheating, so that the temperature at the lower area is low, and accidents such as fused salt solidification, tube explosion of a heat absorption tube and the like are easily caused.
Disclosure of Invention
The invention is provided in view of the above technical problems, and an object of the invention is to provide a thermal insulation device for a solar tower-type heat absorber, which stores solar energy in the form of internal energy through a reduction reaction of a chemical heat storage substance at an initial stage of preheating, and when light is concentrated in a heliostat field, the temperature of the chemical heat storage substance is reduced, the stored energy is released through an oxidation reaction and heats gas, and the heated gas is discharged through a hood and is blown to heat the lower end of a heat absorption tube, so that the temperature balance of the whole heat absorption tube is ensured.
Specifically, the invention provides a thermal insulation device for a solar tower-type heat absorber, which is used for performing thermal insulation treatment on a heat absorption pipe of the tower-type heat absorber and comprises the following steps:
the heat storage unit comprises porous metal and chemical heat storage substances loaded on the porous metal, and the porous metal is used as a frame body of the heat storage unit and is arranged on the periphery of a lower header of the tower type heat absorber;
the air flow pipeline is arranged inside the heat storage unit, and an inlet and an outlet of the air flow pipeline are formed on the surface of the heat storage unit;
the air inlet device is connected with the inlet of the airflow pipeline and is used for introducing high-pressure air into the airflow pipeline;
the exhaust pipeline is connected with the outlet of the airflow pipeline, and the air in the airflow pipeline is exhausted by utilizing a plurality of hoods, and the exhaust holes of the hoods face to one side of the lower header, which is connected with the heat absorption pipe;
and the thermocouple detects the temperature of the heat storage unit.
Compared with the prior art, the solar tower type heat absorber heat preservation device provided by the invention has the advantages that in the initial preheating stage, the condensation of the heliostat field is dispersed, the reflected sunlight irradiates the heat storage unit at the lower collection box, the solar energy is stored in the form of internal energy through the reduction reaction of the chemical heat storage substances, when the condensation of the heliostat field is concentrated, the temperature of the thermal chemical heat storage substances is reduced, the stored energy is released into heating gas through the oxidation reaction, the heated gas enters the exhaust pipeline and is exhausted outwards through the hood, and the heating gas is blown to heat the lower end of the heat absorption pipe. Therefore, the temperature of the lower end of the heat absorption pipe during preheating is improved, the temperature difference between the upper end and the lower end of the heat absorption pipe is reduced, and the overall temperature balance of the heat absorption pipe is kept.
Preferably, the inlet of the air flow duct is disposed on a side of the heat storage unit away from the heat absorption pipe, the outlet of the air flow duct is disposed on a side of the heat storage unit close to the heat absorption pipe, and the exhaust duct has an annular structure and circumferentially surrounds the side of the heat storage unit close to the heat absorption pipe.
According to the preferred scheme, the position of the inlet of the airflow pipeline is provided with the air inlet device, and the position of the outlet of the airflow pipeline is provided with the air cap which is convenient to arrange. And gas flows into the annular exhaust pipeline from the airflow pipeline, so that the gas is blown to the circumferential direction of the bottom of the heat absorption pipe, and the bottom of the heat absorption pipe is uniformly heated.
Further, preferably, the air flow duct is formed in a spiral shape and is wound in a circumferential direction of the heat storage unit.
According to the preferred embodiment, the spiral gas flow pipe increases the gas flow path, prolongs the heating time of the gas, and enables the gas to be heated effectively and the gas with higher temperature to heat the lower end of the heat absorption pipe better.
Preferably, the top of the hood is hemispherical, the lower end of the hood is cylindrical, the exhaust hole is formed in the top, the lower end of the hood is of a hollow structure and is communicated with the exhaust hole, and the lower end of the hood is in sliding fit with the outlet of the exhaust pipeline.
According to the preferred scheme, when high-pressure gas flows through the blast cap, the blast cap rises to release the exhaust hole, so that the exhaust is realized. When no gas flows or low-pressure gas flows through the blast cap, the blast cap is not moved, the exhaust hole is sealed, and sealing is realized.
Further, preferably, the hood is fixedly connected to the exhaust pipeline, and a petal-shaped blocking piece is arranged at an opening at one end of the hood, which is connected with the exhaust pipeline.
According to the preferred scheme, when high-pressure gas flows through the blast cap, the petal-shaped retaining pieces are bent, and the high-pressure gas enters the blast cap and is discharged from the exhaust hole, so that exhaust is realized.
Preferably, the plurality of thermocouples are distributed along the circumferential direction of the heat storage unit, and the plurality of thermocouples are not inserted into the heat storage unit to the same depth.
According to the preferred scheme, the thermocouples detect the temperature at different positions and depths of the heat storage unit, so that the temperature change of the heat storage unit can be comprehensively detected and accurately reflected.
In addition, as a preferred option, the thermal insulation device for the solar tower type heat absorber further comprises a control module which is in communication connection with both the air inlet device and the thermocouple.
According to the preferred scheme, the control module can automatically control the action of the air inlet device according to the temperature of the heat storage unit detected by the thermocouple, so that the automation and the intellectualization of the heat preservation work of the heat preservation device of the solar tower type heat absorber are realized.
Preferably, the thermal insulation apparatus for a solar tower heat absorber further includes a flow controller provided between the airflow duct and the air intake device in communication with each other.
According to the preferred scheme, the flow controller can adjust the gas entering the gas flow pipeline, so that the requirements of different temperatures in the heat storage unit are met, and the temperature of the gas at the outlet of the gas flow pipeline fluctuates within a certain range.
Preferably, the heat storage unit is provided with a metal casing wrapped around the porous metal.
According to the preferred scheme, the metal shell wrapping the heat storage unit can prevent the chemical heat storage substances from falling off from gaps of the porous metal, and the overall stability of the heat storage unit is kept.
The invention also provides a heat preservation method of the heat preservation device of the solar tower type heat absorber, which is used for preserving heat of the heat absorption pipe by using the heat preservation device of the solar tower type heat absorber in any technical scheme and comprises the following steps:
in the initial preheating stage, the heliostat reflects sunlight to the heat storage unit, and the heat storage unit is heated to raise the temperature;
when the temperature of the chemical heat storage substance is higher than a first preset temperature, the chemical heat storage substance performs a reduction reaction to absorb heat, and the heat is stored in the form of internal energy of the chemical heat storage substance;
after the heliostat field condensation is concentrated, the temperature of the heat storage unit is gradually reduced;
when the temperature of the chemical heat storage substance is lower than a second preset temperature, the chemical heat storage substance generates oxidation reaction and releases heat, and energy stored in the chemical heat storage substance is released;
when the thermocouple detects that the temperature of the heat storage unit is higher than the starting temperature, the air inlet device is started;
the air inlet device introduces high-pressure air into an airflow pipeline inside the heat storage unit, the air absorbs sensible heat of the porous metal and the chemical heat storage substances and heat released by the reaction of the chemical heat storage substances in the process of circulating in the airflow pipeline and heats up, the heated air enters an exhaust pipeline, changes the flowing direction and the air speed through a hood, is discharged, and is blown towards the bottom of the heat absorption pipe to heat the heat absorption pipe;
and when the thermocouple detects that the temperature of the heat storage unit is lower than the starting temperature, closing the air inlet device.
Compared with the prior art, the heat preservation method of the heat preservation device of the solar tower type heat absorber provided by the invention has the advantages that solar energy is stored in an internal energy form through the reduction reaction of the chemical heat storage substances in the initial preheating stage, when light is concentrated, the temperature of the chemical heat storage substances is reduced, the stored energy is released through the oxidation reaction and heats gas, the heated gas enters the exhaust pipeline and then is exhausted outwards through the hood, and the lower end of the heat absorption pipe is heated through blowing. Therefore, the temperature of the lower end of the heat absorption pipe during preheating is improved, the temperature difference between the upper end and the lower end of the heat absorption pipe is reduced, and the overall temperature balance of the heat absorption pipe is kept.
Drawings
FIG. 1 is a schematic diagram of a tower heat absorber according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a thermal insulation device for a solar tower-type heat absorber in a first embodiment of the invention;
FIG. 3 is a schematic cross-sectional view taken along line A-A of FIG. 2;
FIG. 4 is a schematic cross-sectional view of the hood of FIG. 3;
FIG. 5 is a schematic partial cross-sectional view of the heat storage unit of FIG. 3;
fig. 6 is a schematic structural view of a hood in a second embodiment of the present invention.
Description of reference numerals:
1. a heat absorbing tube; 2. a lower header; 3. a heliostat; 4. a heat storage unit; 41. a porous metal; 42. a chemical heat storage substance; 43. a metal housing; 5. an air flow conduit; 6. an air intake device; 7. an exhaust duct; 71. an air outlet pipe orifice; 8. a thermocouple; 9. a hood; 91. an exhaust hole; 92. the top of the hood; 93. the lower end of the hood; 94. petal-shaped retaining pieces; 10. a control module; 11. a flow controller.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings. The structure and the like of the solar tower type heat absorber thermal insulation device are schematically and simply shown in the attached drawings.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Referring to fig. 1, in the tower type heat absorber, a lower header 2 is arranged in a cylindrical shape, and a heat absorbing pipe 1 is connected with the top end of the lower header 2. The diameter of the platform of the lower header 2 is larger than the outer diameter of the columnar screen enclosed by the heat absorption tubes 1. When heliostat 3 reflects the sunlight, lower header 2 platform can lead to the fact the sheltering from to heat absorption pipe 1 bottom, and the heat absorption pipe 1 bottom is received and is shone, and heat absorption pipe 1 top temperature is high and the bottom temperature is low excessively, takes place easily that heat absorption pipe 1 thermal stress is too big and warp, may cause accidents such as heat absorption pipe 1 explosion even.
Therefore, the invention provides a heat preservation device of a solar tower type heat absorber, when the temperature of the lower area of the light receiving surface of a heat absorbing pipe 1 is low, the bottom of the heat absorbing pipe 1 is blown by hot gas to locally heat the heat absorbing pipe 1, and the temperature balance of the whole heat absorbing pipe 1 is kept.
Implementation mode one
The first embodiment of the invention provides a solar tower type heat absorber thermal insulation device, which comprises a heat storage unit 4, an airflow pipeline 5 arranged inside the heat storage unit 4, an air inlet device 6 connected with an inlet of the airflow pipeline 5, an exhaust pipeline 7 connected with an outlet of the airflow pipeline 5 and a thermocouple 8 for measuring the temperature of the heat storage unit 4, wherein the exhaust pipeline 7 utilizes a hood 9 to exhaust the gas in the airflow pipeline 5.
More specifically, as shown in fig. 2 and 3, the heat storage unit 4 is wrapped around the lower header 2, and includes a porous metal 41 formed as a frame body of the heat storage unit 4, and a chemical heat storage substance 42 is loaded on the porous metal 41. The porous metal 41 is made of micro spheroids (commonly called powder) through high-temperature sintering, tiny pores are distributed in all directions inside the metal, and the gaps of the porous metal 41 are filled with the chemical heat storage substance 42. The air inlet device 6 introduces air into the air flow pipeline 5 through the inlet of the air flow pipeline 5, and the air exhausted from the air flow pipeline 5 is exhausted by the exhaust pipeline 7 and the blast cap 9 on the exhaust pipeline.
Because the resistance at the blast cap 9 is large, the gas needs to be lifted from the normal pressure to a certain pressure to overcome the pressure loss in the gas flowing process. The air inlet means 6 may be an air compressor or an evaporator, so that high pressure air or water vapor is introduced into the air flow duct 5, both gases being easily available and pollution-free.
Here, the outer periphery of the lower header 2 refers to the outer periphery of the side surface of the lower header 2 excluding the top end and the bottom end, and in the present embodiment, the lower header 2 has a cylindrical shape, the outer periphery of the lower header 2 has a cylindrical side surface, and the heat storage units 4 are annularly enclosed in the lower header 2.
The porous metal 41 may be a copper foam, which serves as a carrier of the chemical heat storage substance 42, and has the advantages of good thermal conductivity, high temperature resistance, and no reaction with the chemical heat storage substance 42 at high temperature. On one hand, the chemical heat storage material 42 can rapidly transmit the external temperature to the chemical heat storage material 42, and on the other hand, the external temperature change and the temperature change of the chemical heat storage material 42 during the oxidation or reduction reaction can also be transmitted to the exhaust pipe 7 through the porous metal 41.
The chemical heat storage material 42 is a material that chemically reacts with a change in temperature to absorb and release heat. In the present embodiment, the chemical heat storage material 42 is a metal oxide, and further an oxide of iron, cobalt, or copper.
Based on the structure of the heat preservation device for the solar tower-type heat absorber, the embodiment further provides a heat preservation method for the heat preservation device for the solar tower-type heat absorber, which comprises the following steps:
in the initial preheating stage, the heliostat 3 reflects sunlight to the heat storage unit 4, and the heat storage unit 4 is heated to raise the temperature;
when the temperature of the chemical heat storage substance 42 is higher than the first preset temperature T1When the chemical heat storage substance 42 is in the reducing reaction, the chemical heat storage substance absorbs heat, and the heat is stored in the form of internal energy of the chemical heat storage substance 42;
after the heliostat field is concentrated in light condensation, the temperature of the heat storage unit 4 is gradually reduced;
when the temperature of the chemical heat storage substance 42 is lower than the second preset temperature T2In the meantime, the chemical heat storage substance 42 generates oxidation reaction to release heat, and releases energy stored in the chemical heat storage substance 42;
when the thermocouple 8 detects that the temperature of the heat storage unit 4 is higher than the starting temperature T3When the air inlet device 6 is opened;
the air inlet device 6 introduces high-pressure air into the air flow pipeline 5 in the heat storage unit 4, the air absorbs sensible heat of the porous metal 41 and the chemical heat storage substance 42 in the process of flowing in the air flow pipeline 5 and absorbs heat released by the reaction of the chemical heat storage substance 42 and heats up, the heated air enters the exhaust pipeline 7, changes the flowing direction and the air speed through the hood 9 and is discharged, and the heated air is blown towards the bottom of the heat absorption pipe 1 to heat the heat absorption pipe 1;
when the thermocouple 8 detects that the temperature of the heat storage unit 4 is lower than the starting temperature T3When this occurs, the air intake device 6 is closed.
Specifically, in the initial stage of preheating, the solar tower-type heat absorber thermal insulation device transfers solar energy reflected by the heliostat 3 onto the platform of the lower header 2 to the heat storage unit 4, the porous metal 41 in the heat storage unit 4 is first heated, and as the porous metal 41 is heated, the porous metal 41 transfers heat to the chemical heat storage substance 42 loaded thereon. When the temperature of the chemical heat storage substance 42 rises to the first preset temperature T1During the process, the chemical heat storage substance 42 is subjected to a reduction reaction to absorb heat, thereby converting solar energy into chemical energyThe form is stored inside the chemical heat storage substance 42.
After the heliostat field is concentrated, sunlight irradiated on the platform of the lower header 2 is reduced, the porous metal 41 in the heat storage unit 4 is firstly cooled, and the temperature of the chemical heat storage substance 42 loaded on the porous metal 41 is gradually reduced along with the cooling of the porous metal 41. When the temperature of the chemical heat storage substance 42 is lowered to the second preset temperature T2At this time, the chemical heat storage material 42 is oxidized to release heat, and the energy stored in the chemical heat storage material 42 is released.
The thermocouple 8 detects the temperature on the heat storage unit 4:
when the thermocouple 8 detects that the temperature of the heat storage unit 4 is higher than the starting temperature T3When the solar tower type heat absorber heat preservation device is in operation, the air inlet device 6 is started, high-pressure air is introduced into the airflow pipeline 5, and the air is not heated and is low in temperature. In the process of circulating in the airflow pipeline 5, the low-temperature gas is heated by sensible heat of the high-temperature porous metal 41 and the chemical heat storage substance 42 and heat released after oxidation reaction of the chemical heat storage substance 42, and then is heated, and the heated high-temperature gas enters the exhaust pipeline 7, is discharged through the hood 9, and heats the bottom of the heat absorption pipe 1 through blowing.
When the thermocouple 8 detects that the temperature of the heat storage unit 4 is lower than the starting temperature T3When the air inlet device 6 is closed, the air is stopped from being introduced into the air flow pipeline 5, and the heat preservation device of the solar tower type heat absorber stops working.
Starting temperature T3Can be set to a second preset temperature T2Or higher or lower than the second preset temperature T2Preferably the starting temperature T3And a second predetermined temperature T2The difference is not more than 20 ℃. According to the arrangement, high-pressure gas can be introduced as soon as possible while the chemical heat storage substance 42 releases heat, or before and after the temperature of the bottom of the heat absorption tube 1 is greatly reduced, the gas is heated by utilizing the heat released by the reaction of the chemical heat storage substance 42, the bottom of the heat absorption tube 1 is blown, the heat absorption tube 1 is heated in time, the temperature of the whole heat absorption tube 1 is kept balanced and consistent, and the overlarge thermal stress caused by the large temperature difference between the upper part and the lower part of the heat absorption tube 1 is avoidedAnd deformation, accidents such as tube explosion of the heat absorption tube 1 are avoided.
In the practical application of the present embodiment, iron oxide (Fe)2O3) As an example of the chemical heat storage substance 42, the first predetermined temperature T1Is 1000 ℃, and a second preset temperature T2At 600 ℃ and a start temperature T3The temperature was 580 ℃.
According to the heat preservation device and the heat preservation method for the solar tower type heat absorber, the heat preservation device for the solar tower type heat absorber is installed in the peripheral space of the lower header 2, the structural design is reasonable, additional space does not need to be arranged, and the occupied space is small.
The thermocouple 8 can be used for monitoring the temperature change of the heat storage unit 4 in real time, so that gas is introduced in time according to the temperature change, and the bottom of the heat absorption pipe 1 is locally heated after the heat released by the heat storage unit 4 is absorbed. The heat storage unit 4 is additionally arranged outside the lower header 2 of the heat absorber, so that a certain heat preservation effect is also achieved on the lower header 2, the design thickness of a heat preservation layer of the lower header 2 can be reduced, materials are saved, and the cost is saved.
The thermocouples 8 are preferably provided in plurality, the thermocouples 8 are uniformly distributed along the circumferential direction of the heat storage unit 4, and the depth of the thermocouples 8 inserted into the heat storage unit 4 is not all the same, and preferably is different. Through a plurality of thermocouples 8 arranged at different positions and depths of the heat storage unit 4, the temperature change of the heat storage unit 4 can be comprehensively detected and accurately reflected.
The hood 9 can respectively play exhaust and sealing roles in different working conditions, can realize constant pressure and directional exhaust after the pressure in the airflow pipeline 5 reaches a specific value, and can fall down when the pressure in the airflow pipeline 5 does not reach the specific value, thereby playing a sealing role.
In the present embodiment, the solar energy reflected to the lower header 2 stage of the heat absorber by the heliostat 3 is converted into the chemical energy of the chemical heat storage substance 42 itself, the sensible heat of the porous metal 41 and the loaded chemical heat storage substance 42, and the stored heat is utilized by the high-pressure gas, thereby effectively improving the utilization efficiency of the solar energy.
In addition, when the tower type heat absorber is started in the morning, the heat preservation device of the solar tower type heat absorber is started at the same time, hot gas is blown to the bottom of the heat absorption pipe 1, the heat absorber can be preheated, and the starting time of the heat absorber is shortened.
The inlet of the air flow pipe 5 is arranged below the heat storage unit 4, namely, on the side far away from the heat absorption pipe 1, and is arranged lower, so that the air inlet device 6 and a flow controller 11 which will be described later are convenient to arrange, and the air inlet device is prevented from being arranged on the upper platform of the lower header 2 to shield the heat absorption pipe 1. The outlet of the airflow pipeline 5 is arranged above the heat storage unit 4, namely on one side close to the heat absorption pipe 1, and the outlet is close to the heat absorption pipe 1, so that the wind cap 9 is convenient to arrange. In addition, the gas with lower temperature is introduced from the bottom of the gas flow pipeline 5, the density is gradually reduced in the temperature rising process, the gas can automatically move upwards, and the gas is exhausted after the blast cap 9 is burst in the exhaust pipeline 7.
The exhaust pipeline 7 is of an annular structure, the top of the heat storage unit 4 surrounds the heat storage unit 4 in the circumferential direction, small openings are uniformly formed in the top of the exhaust pipeline 7 at intervals, and wind caps 9 are installed. The heating and heat-absorbing exhaust pipeline 7 is annularly arranged at the top of the heat storage unit 4, and the heat absorption pipe 1 of the tower type heat absorber can be uniformly blown and heated annularly by using the hood 9, so that the temperature of the upper end and the lower end of the heat absorption pipe 1 is kept balanced and stable.
If the distance between the exhaust pipeline 7 and the heat absorption pipe 1 is too close, the blast cap 9 can only blow to the bottommost part of the heat absorption pipe 1, and the heating area is small; if the distance between the exhaust duct 7 and the heat absorbing pipe 1 is too long, the temperature of the gas purged to the heat absorbing pipe 1 is lowered, and the heat loss is large. The distance between the exhaust pipeline 7 and the heat absorption pipe 1 is 10-15cm, so that the heating area of the hood 9 on the heat absorption pipe 1 can be increased under the condition of reducing the heat loss of gas.
Referring to fig. 2 and 3, there are a plurality of hoods 9, and a plurality of hoods 9 are uniformly distributed on the exhaust duct 7, that is, uniformly distributed along the circumferential direction of the heat storage unit 4, so that the hot gas blown out from the plurality of hoods 9 can uniformly purge the lower end of the heat absorption pipe 1, and the heat absorption pipe 1 is uniformly heated to maintain a constant temperature. The high-temperature gas entering the exhaust pipeline 7 can change the flowing direction and the wind speed of the gas through the wind cap 9, so that the gas blows against the lower end of the heat absorption pipe 1 to heat the heat absorption pipe 1.
If the number of the blast caps 9 is large and the distance between the adjacent blast caps 9 is small, the flow velocity of the high-temperature gas is low, the height of the purging heat absorption pipe 1 is low, and the heat loss is large; if the number of the hoods 9 is small, the partial area of the heat absorbing pipe 1 does not receive heat from the high temperature gas, the uniform heating effect is not obtained, and the resistance loss is large. Therefore, for the heat absorber with the diameter of about 10m, the distance between the adjacent hoods 9 is 15-20cm, the number is 80-100, and multiple areas of the heat absorbing pipe 1 are uniformly heated under the condition that the blowing height of the hoods 9 is ensured, and meanwhile, the resistance loss is reduced.
Referring to fig. 4, the top 92 of the hood is hemispherical, and the top 92 of the hood has a smooth shape and low wind resistance. The blast cap 9 and the exhaust duct 7 are arranged in a sliding manner, specifically, the lower end 93 of the blast cap is cylindrical and is of a hollow structure, the exhaust duct 7 is provided with an outlet pipe opening 71 at a small opening, and the lower end 93 of the blast cap is in sliding fit with the outlet pipe opening 71. The top 92 of hood is equipped with a plurality of exhaust holes 91 that communicate with the lower extreme 93 of hood to realize the multi-angle of hood 9 and exhaust, can all-roundly sweep the lower part of heat-absorbing pipe 1 during ventilating. When the high-pressure gas flows through the hood 9, the hood 9 rises to release the exhaust hole 91, thereby realizing the exhaust. When no gas flows or low-pressure gas flows through the blast cap 9, the blast cap 9 is not moved, the exhaust hole 91 is sealed, and sealing is realized.
The airflow pipeline 5 is spirally arranged around the circumference of the heat storage unit 4, so that the circulation path and time of the gas introduced by the gas inlet device 6 in the airflow pipeline 5 are increased, and the heated gas is fully heated.
The solar tower-type heat absorber heat preservation device further comprises a control module 10, and the thermocouple 8 and the air inlet device 6 are in communication connection with the control module 10. The thermocouple 8 detects the temperature of the heat storage unit 4 in real time, temperature information is transmitted to the control module 10, and the control module 10 controls the starting or braking of the air inlet device 6 according to the received temperature information, so that the automation and the intellectualization of the action of the heat preservation device of the solar tower type heat absorber are realized.
The heat preservation device of the solar tower type heat absorber further comprises a flow controller 11, and an inlet and an outlet of the flow controller 11 are respectively connected with the airflow pipeline 5 and the air inlet device 6, so that the flow of air in the air inlet device 6 can be controlled. The flow controller 11 adjusts the flow rate of the gas entering the gas flow pipe 5, so as to adapt to the requirements of different temperatures inside the heat storage unit 4, and the temperature of the gas at the outlet of the gas flow pipe 5 fluctuates within a certain range. When the temperature in the heat storage unit 4 is higher, a larger flow is selected; when the temperature inside the heat storage unit 4 is low, the gas flow rate is reduced.
The flow controller 11 may also be communicatively connected to the control module 10 to achieve precise and automated operation under the control of the control module 10. The control module 10 may be provided independently of the other components, or may be provided inside the thermocouple 8 or the flow controller 11, and the specific location thereof is not strictly specified.
The air flow pipe 5 is made of metal, has excellent heat conduction performance and fast heat transfer, and can transfer sensible heat of the porous metal 41 and the chemical heat storage substance 42 loaded on the porous metal and chemical energy of the chemical heat storage substance 42 to gas through the air flow pipe 5.
If the diameter of the gas flow pipeline 5 is smaller, the flow resistance of the high-pressure gas is larger, and the gas inlet device 6 needs to provide higher power; if the diameter of the gas flow pipeline 5 is too large, the tube pass is short, the heat absorbed by the high-pressure gas is reduced, and the temperature of the outlet is low. Therefore, the diameter of the airflow pipeline 5 is set to be 8-12cm, the flow resistance of high-pressure gas is reduced on the premise of ensuring the tube pass of the airflow pipeline 5, and the power required by the air inlet device 6 is reduced.
Referring to fig. 5, the outer side of the heat storage unit 4 is further wrapped with a metal shell 43, the metal shell 43 wraps the porous metal 41 to prevent the chemical heat storage substance 42 from falling off from gaps of the porous metal 41, and the heat storage unit can also play a certain role in heat preservation and protection to prevent the heat storage unit 4 from being damaged by external force.
Second embodiment
The second embodiment of the invention provides a thermal insulation device for a solar tower-type heat absorber, which is a further improvement of the first embodiment, and parts which are not particularly described include reference numerals and text descriptions, which are the same as those of the first embodiment, and are not described again here.
The main improvement of the second embodiment over the first embodiment is that in the second embodiment of the present invention, as seen in fig. 6, the lower end 93 of the hood is fixedly connected to the exhaust duct 7, a petal-shaped baffle 94 is disposed at an opening at one end of the lower end 93 of the hood connected to the exhaust duct 7, and the exhaust hole 91 is disposed inside the hood 9. When high-pressure gas flows through the hood 9, the petal-shaped blocking pieces 94 are bent, and the high-pressure gas enters the hood 9 and is discharged from the exhaust hole 91, so that exhaust is realized. When no gas flows or low-pressure gas flows through the blast cap 9, the petal-shaped blocking pieces 94 are not moved, and the high-pressure gas cannot enter the blast cap 9, so that sealing is realized.
It is obvious to those skilled in the art that the respective steps of the above-described control method can be deleted or adjusted in order as necessary within the scope of the technical idea of the present invention.
It will be appreciated by those of ordinary skill in the art that in the embodiments described above, numerous technical details are set forth in order to provide a better understanding of the present application. However, the technical solutions claimed in the claims of the present application can be basically implemented without these technical details and various changes and modifications based on the above embodiments. Accordingly, in actual practice, various changes in form and detail may be made to the above-described embodiments without departing from the spirit and scope of the invention.

Claims (10)

1. The utility model provides a solar energy tower heat absorber heat preservation device, keeps warm to the heat absorption pipe of tower heat absorber and handles, its characterized in that includes:
the heat storage unit comprises porous metal and chemical heat storage substances loaded on the porous metal, and the porous metal is used as a frame body of the heat storage unit and is arranged on the periphery of a lower header of the tower type heat absorber;
the air flow pipeline is arranged inside the heat storage unit, and an inlet and an outlet of the air flow pipeline are formed on the surface of the heat storage unit;
the gas inlet device is connected with the inlet of the gas flow pipeline and is used for introducing high-pressure gas into the gas flow pipeline;
the exhaust pipeline is connected with the outlet of the airflow pipeline, and the air in the airflow pipeline is exhausted by utilizing a plurality of air hoods, and the exhaust holes of the air hoods face to one side of the lower header, which is connected with the heat absorption pipe;
and the thermocouple detects the temperature of the heat storage unit.
2. The solar tower-type heat absorber heat preservation device according to claim 1, wherein an inlet of the airflow pipeline is arranged on one side of the heat storage unit far away from the heat absorption pipe, an outlet of the airflow pipeline is arranged on one side of the heat storage unit close to the heat absorption pipe, and the exhaust pipeline is of an annular structure and circumferentially surrounds one side of the heat storage unit close to the heat absorption pipe.
3. A solar tower heat absorber insulation as claimed in claim 1, wherein the air flow duct is helical and is coiled circumferentially around the heat storage unit.
4. A solar tower heat absorber insulation device according to any one of claims 1-3, wherein the top of the hood is hemispherical, the lower end of the hood is cylindrical, the vent hole is formed in the top, the lower end is hollow and is in communication with the vent hole, and the lower end is in sliding fit with the outlet of the vent pipe.
5. A solar tower heat absorber thermal insulation device according to any one of claims 1-3, wherein the hood is fixedly connected to the exhaust duct, and a petal-shaped baffle is arranged at an opening at one end of the hood connected to the exhaust duct.
6. The thermal absorber insulation device of a solar tower-type heat absorber according to claim 1, wherein the thermocouples are distributed along the circumferential direction of the heat storage unit, and the depth of the thermocouples inserted into the heat storage unit is not all the same.
7. The solar tower heat absorber insulation of claim 1, further comprising:
and the control module is in communication connection with the air inlet device and the thermocouple.
8. A solar tower heat absorber thermal insulation device according to any one of claims 1-3 and 6-7, further comprising:
and the flow controller is communicated and arranged between the airflow pipeline and the air inlet device.
9. A solar tower heat absorber thermal insulation device according to any one of claims 1-3 and 6-7, wherein the heat storage unit is provided with a metal shell wrapping the outer side of the porous metal.
10. A heat preservation method for a heat preservation device of a solar tower-type heat absorber, which is characterized in that the heat preservation device of any one of claims 1 to 9 is used for preserving heat of the heat absorption tube, and comprises the following steps:
in the initial preheating stage, the heliostat reflects sunlight to the heat storage unit, and the heat storage unit is heated to raise the temperature;
when the temperature of the chemical heat storage substance is higher than a first preset temperature, the chemical heat storage substance performs a reduction reaction to absorb heat, and solar energy is stored in the form of internal energy of the chemical heat storage substance;
after the heliostat field condensation is concentrated, the temperature of the heat storage unit is gradually reduced;
when the temperature of the chemical heat storage substance is lower than a second preset temperature, the chemical heat storage substance generates oxidation reaction and releases heat, and energy stored in the chemical heat storage substance is released;
when the thermocouple detects that the temperature of the heat storage unit is higher than the starting temperature, the air inlet device is started;
the air inlet device introduces high-pressure air into an airflow pipeline in the heat storage unit, the air absorbs sensible heat of the porous metal and the chemical heat storage substances and heat released by the reaction of the chemical heat storage substances in the process of flowing in the airflow pipeline and heats up, the heated air enters an exhaust pipeline, changes the flowing direction and the air speed through an air cap, is discharged, and blows towards the bottom of the heat absorption pipe to heat the heat absorption pipe;
and when the thermocouple detects that the temperature of the heat storage unit is lower than the starting temperature, closing the air inlet device.
CN202010196096.9A 2020-03-19 2020-03-19 Heat preservation device and heat preservation method for solar tower type heat absorber Active CN113494780B (en)

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