NO345513B1 - Thermal energy battery - Google Patents

Thermal energy battery Download PDF

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Publication number
NO345513B1
NO345513B1 NO20190853A NO20190853A NO345513B1 NO 345513 B1 NO345513 B1 NO 345513B1 NO 20190853 A NO20190853 A NO 20190853A NO 20190853 A NO20190853 A NO 20190853A NO 345513 B1 NO345513 B1 NO 345513B1
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Norway
Prior art keywords
vapor
tes
line
thermal energy
superheater
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NO20190853A
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Norwegian (no)
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NO20190853A1 (en
Inventor
Pål G Bergan
Christopher Johan Greiner
Nils Høivik
Martin Skottene
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Energynest As
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Application filed by Energynest As filed Critical Energynest As
Priority to NO20190853A priority Critical patent/NO345513B1/en
Priority to AU2020292109A priority patent/AU2020292109A1/en
Priority to EP20821624.2A priority patent/EP3983744A4/en
Priority to MA056210A priority patent/MA56210A/en
Priority to US17/612,494 priority patent/US11709024B2/en
Priority to CN202080042115.0A priority patent/CN113994167B/en
Priority to PCT/NO2020/050159 priority patent/WO2020251373A1/en
Publication of NO20190853A1 publication Critical patent/NO20190853A1/en
Publication of NO345513B1 publication Critical patent/NO345513B1/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D20/00Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01KSTEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K1/00Steam accumulators
    • F01K1/10Steam accumulators specially adapted for superheated steam
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01KSTEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K1/00Steam accumulators
    • F01K1/12Multiple accumulators; Charging, discharging or control specially adapted therefor
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D20/00Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
    • F28D20/0034Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/14Thermal energy storage

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Primary Cells (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Description

THERMAL ENERGY BATTERY
Technical Field
The present invention relates to thermal energy batteries and operation thereof. More specifically, the invention relates to a thermal energy battery integrated into or coupled to a power plant, an energy storage system or an energy delivery system, or any combinations thereof, feasible for thermal energy charging, storage and discharging according to demand.
Background Art
Most of the electric power generated currently is generated in power plants using steam, and to some extent other fluid, such as organic fluid or mixtures thereof. In order to avoid shortage of energy, it is vital to avoid waste of energy. Battery technology, in various embodiments, is essential to minimize waste of energy. High variation in energy production by sources, particularly renewable sources, makes thermal energy batteries feasible. Start, stop and variation in modes of operation in power plants also make thermal batteries feasible.
Simplification of power plants, increased versatility with respect to operation parameters, reducing cost and complexity, will also be beneficial, if achievable.
Waste heat recovery for energy efficiency improvement, and also electrification of industrial processes in a power market with fluctuating prices, are other possible use cases beyond steam power plants, with respect to thermal energy storage.
Currently, thermal energy batteries are typical latent heat batteries, based on solid-fluid phase change materials for thermal energy storage, as an essential component.
For example, the CCT (Climate Change Technologies Pty Ltd) Energy Storage TED-thermal energy device- is based on latent heat as an essential component for functionality, cf. patent publication WO 2018/201193 A1. Another example is described and illustrated in patent publication US 2015/0219403 A1. In paragraphs 18 and 19 of US 2015/0219403 A1, it is described that direct storage in concrete has been found to create reliability problems and low efficiency. In addition, it is described that thermal storage systems with direct steam generation according to the state of the art are more complex than oil storage systems, and this is why their estimated cost is higher than it is for oil units, for large plants.
Further relevant technology is described in the patent publications US 2008/0022713 A1, WO 2019/038292 A1, US 2011/0162400 A1, US 2018/0292097 A1 and DE 102014216597 A1. However, none of said publications include description or illustrations of a technology concept enabling how to receive steam, storing thermal energy contained in said steam while also storing said steam.
The objective of the present invention is to provide an alternative thermal energy battery.
Summary of invention
The invention meets the objective by providing a thermal energy battery comprising:
an evaporator-condenser thermal energy storage (ec-TES), with an end for vapor and an end for liquid, comprising one-phase stationary material storing at least 70% of the thermal energy stored within the ec-TES,
a storage tank for vapor and liquid (ST), with a vapor part at a higher elevation and a liquid part at a lower elevation,
a vapor line, arranged to the vapor end of the ec-TES, for inlet and outlet of vapor,
a liquid line arranged between the liquid end of the ec-TES and the liquid part of the ST,
a tank vapor line arranged from the vapor part of the ST to the vapor line, and
an evaporation control valve (CV6) in the tank vapor line.
The vapor and the liquid are in many embodiments steam and water, respectively. In other embodiment the vapor and liquid are an organic compound or a mixture of compounds. Cyclo-pentane is one example. Isobutane is another example. Mixtures feasible for use in organic Rankine cycles, such as R134a or R134a and iso-butane are further examples.
The phrase “a tank vapor line arranged from the vapor part of the ST to the vapor line”, means any operative arrangement for fluid flow as intended. A combined coupling to the vapor end of the ec-TES is one embodiment, another is a three-way coupling in the vapor line at elevation above the vapor end of the ec-TES.
Terminology such as vapor end, liquid end, vapor part, liquid part, vapor line, tank vapor line and liquid line, refers to the contents of the units or parts/ends thereof or lines/conduits, under normal operating conditions.
Terminology like high elevation and low elevation, higher elevation and lower elevation, are relative within one unit.
The ec-TES will in operation typically contain two-phase vapor-liquid as a Heat Transfer Fluid (HTF), with single-phase vapor at the vapor end and singlephase liquid, or in substance liquid, typically above 70 or 80 % liquid by mass during charging, at the liquid end. Pressure-temperature and resulting evaporation and condensation and flow of HTF within the TES, typically control the processes providing a liquid end and a vapor end of the ec-TES. If the vapor end is at a higher elevation and the liquid end is at a lower elevation, which is not obligatory, gravity will contribute to said processes within the e-TES.
The “evaporator-condenser thermal energy storage (ec-TES), comprising onephase stationary material storing at least 70% of the thermal energy stored within the ec-TES”, means that the ec-TES is no storage tank containing a larger volume filled with HTF during normal operation, and no thermal energy storage containing phase change material, except HTF, the heat transfer fluid used for charging and discharging thermal energy. More specifically, if the HTF, thermal insulation, support structure and space (typically air) between or around the modules and the elements within a module is disregarded, the ec-TES consists of only one-phase thermal energy storage material, preferably solid one-phase material, up to 90 or 100% by weight, and above 60 %, more preferably above 70 or 80 % by volume. Disregarding thermal insulation and space between or around modules and elements within modules of the ec-TES, the only ec-TES volume not being one phase thermal energy storage material, is volume inside conduits for flow of HTF and structural material, as will be clear by studying the further description. Further disregarding the inherent minor storage effect of the HTF itself, all thermal energy stored in the ec-TES is sensible heat thermal energy typically stored in concrete, rock, stones, transformer oil, or most preferably, a combination of concrete and steel, with concrete as the major part material and steel for piping, reinforcement and structural frames/elements. In a typical ec-TES, filled with HTF, the inherent minor thermal energy storage of the HTF itself is about 5%, while about 95% is stored in solid one phase material of the ec-TES. The volume of one-phase thermal energy storage material is large compared to the HTF volume within the ec-TES, preferably larger, more preferably 2, 3, 5 or 10 times larger.
The superheater storage, if included, preferably has identical or similar structural design as the ec-TES, but can be of different size or scale, according to demand.
HP -higher pressure- and LP-lower pressure- are relative terminology. A thermal energy battery of the invention, fully charged with for example HP steam, can initially discharge said steam at HP conditions, before pressure and temperature drops.
The evaporation control valve enables control of discharging by merely operating said valve.
The thermal energy battery preferably further comprises one or both of
a check valve in the tank vapor line, open for flow in direction from the ST and closed for flow in the opposite direction, and
a flow control component in the vapor line between a vapor source/recipient and the connection point of the vapor line and the tank vapor line.
The check valve enables natural circulation during low charging flow rate, for more efficient heat balancing between the ST and the ec-TES. However, the thermal energy battery can be operated without a check valve, by keeping the evaporation control valve closed during the charge process, to direct the steam flow through the ec-TES before entering the ST.
The flow control component in the vapor line arranged between the source/recipient and the connection point of the vapor line and the tank vapor line provides increased functionality. Control valves, compressors and turbines are examples on flow control elements.
For many embodiments, the thermal energy battery preferably comprises a superheater thermal energy storage (superheater TES), comprising one-phase stationary material storing at least 70% of the thermal energy stored within the superheater TES, arranged inline or to the vapor line between sources/recipients and the connection point of the vapor line and the tank vapor line. All power systems with sources delivering and/or users feasible for superheated vapor, such as superheated steam, may take advantage of a thermal energy battery of the invention with a superheater TES. The superheater TES enables charging, storage and delivery of superheated vapor, where the HTF in the superheater TES is vapor phase above saturation level, such as superheated steam, for effective generation of electricity. The superheater TES also provides de-superheating of the vapor when charging, ensuring that the vapor from the vapor source is not causing thermal shock to the ec-TES. In some preferable embodiments, the vapor line includes an inlet and/or an outlet for not superheated vapor for sources and users not delivering or requiring superheated vapor, respectively. In some preferred embodiments, the superheater TES comprises pipe heat exchangers and piping components of so-called super alloys, typically nickel based alloys such as Inconel, enabling higher temperatures and/or pressures than carbon steel.
Both the ec-TES and the superheater TES will contain a one-phase stationary material for thermal energy storage different or separated from the HTF described above. The thermal energy is transferred from the HTF to the storage material during charge, and oppositely, from the storage material to the HTF during discharge.
In some embodiments, the thermal energy battery comprises separate vapor lines for inlet and outlet of vapor, wherein the tank vapor line preferably is arranged to an outlet vapor line arranged to the vapor end of the ec-TES, and each vapor line includes a flow control component. This can provide increased versatility, for example when having many thermal batteries of the invention arranged in parallel, or at different pressure-temperature levels. Within one pressure-temperature level, defined as being within inlet and outlet pressure and temperature of a battery, several thermal energy batteries of the invention can be arranged in parallel.
When several pressure levels, such as in combined cycle power plants, the thermal energy battery may have separate inlets and outlets of vapor to the different pressure levels in the power plant. For example, the first part of charging can be operated with the IP (intermediate pressure) line as steam source, and the last part of charging can be operated with the HP (high pressure) line as steam source. The first part of discharging can be operated with the IP line (or the inlet of the IP turbine) as steam recipient, and the last part of discharging can be operated against the LP (low pressure) line or the LP turbine. By operating with the IP line in addition to the HP and the LP lines, the efficiency of the thermal energy battery will increase.
The thermal energy battery preferably further comprises one or more of the features as follows, in any combination:
for embodiments with superheater TES, a superheater bypass line with a valve (CV4), arranged so as to bypass part or all the vapor flow through the superheater TES arranged inline to the vapor line;
for embodiments with superheater TES, a valve (CV5) in the vapor line between the superheater TES and the connection point of the vapor line and the tank vapor line;
a valve (CV1) arranged in the vapor line, controlling a supply of HP (high pressure) vapor to an inlet;
a valve (CV2) arranged in the vapor line, controlling the delivery of LP (low pressure) vapor from an outlet;
a line with a valve (CV3) for injecting HP condensate to the vapor line, for temperature control to avoid overheating, between the source and superheater TES, or for embodiments with no superheater TES, between the source and the connection point of the vapor line and the tank vapor line; and
a drainage line with a valve (CV7), arranged from the liquid line.
The ec-TES, and the superheater TES if present, preferably consists of onephase material, more preferably solid-state, meaning that said storages are sensible thermal energy storages where the thermal energy storage material always is in solid state. The fluid used for charging and discharging, the heat transfer fluid (HTF), is however vapor, received through an inlet when charging and delivered through an outlet when discharging, with said inlet and said outlet both arranged in a vapor side of the thermal energy battery. The HTF will in part condense, and all or most of the condensed HTF will be stored in the storage tank for vapor and liquid, while some of the condensed HTF may be stored in a lower elevation part of the ec-TES, the liquid end thereof, which will be clear from the description to follow.
Preferably, the ST, at least the liquid/lower part thereof, is located at an equal elevation or a lower elevation than the liquid end of the ec-TES.
Preferably, the elevation of the vapor end of the ec-TES is above, preferably far above, the vapor part of the ST.
In some use cases, the energy source is electric power and not waste heat or other kind of steam sources from an external steam cycle. Then there are two options, the first is to use an external conventional electric boiler and charge the thermal energy battery in the same way as any other steam source, with no implications or changes of the thermal energy battery as described. The other option is to integrate the electric resistive heating elements directly inside the existing ST, in which a small extension of the thermal energy battery is required. With this option, a new liquid line to the ST is preferred, where the ST will be filled with liquid during the charge cycle. The heating elements inside the ST will transfer heat to the liquid and vapor, whereby the liquid will boil and evaporate. The vapor will flow through the ec-TES preferably by natural circulation whereby a check valve arranged inline on the existing liquid line is preferred.
Alternatively, circulation is assisted by a circulation pump arranged inline on the existing liquid line. For embodiments with a superheater TES, a new line arranged from the vapor part of the ST to the vapor line between the superheater TES and the steam recipient is required. Within this line, a conventional electric superheater will provide the required level of superheated vapor into the superheater TES. During discharging, the two additional lines (the liquid supply line and for embodiments with superheater TES, the electric superheater line) will be closed, the heating elements are turned off, and the thermal energy battery is operated in the same way as normal.
The ec-TES, and the superheater TES if present, can have numerous embodiments. However, the ec-TES, and the superheater TES if present, preferably comprises numerous closely arranged concrete thermal energy storage elements. All or most of the concrete thermal energy storage elements preferably comprises pipe heat exchangers fully embedded in the concrete between a pipe heat exchanger inlet and a pipe heat exchanger outlet in the same end or part of the element, an outer shell, preferably a metal shell, being a concrete casting form, ring armoring and fluid leakage confiner, wherein the elements are horizontally oriented but vertically stacked, wherein the ec-TES vapor line is at a higher or highest elevation and the ec-TES liquid line is at a lower or lowest elevation. The elements are preferably arranged in a frame structure, termed cassettes, enabling prefabrication, testing, transport and installation of each cassette as one-unit, which cassettes can be stacked or arranged closely, preferably with all piping and coupling in one end or side only. The concrete, the thermal energy storage material of the elements, consists of more than 70 %, more preferably at least 80% or 90% of the weight of each thermal energy storage element.
The thermal energy battery of the invention is preferably arranged inside thermal insulation.
The invention also provides a method of operating a thermal energy battery of the invention. The method is distinguished by the steps: charging by supplying HP vapor, higher pressure vapor, from a source through the vapor line, with the tank vapor line closed or partly closed for the vapor by a closed or partly closed evaporation control valve or a check valve in the tank vapor line, until a maximum or desired pressure and temperature are reached, and discharging LP vapor, lower pressure vapor, to a recipient through the vapor line, controllable at least by the evaporation control valve, until a minimum or desired temperature and pressure is reached.
The evaporation control valve controls the evaporation/boiling process, by controlling the flashing of steam and the condensate flow through the ec-TES, and thereby impacting the temperature difference between the storage material and the HTF.
The feature “with the tank vapor line closed or partly closed for the vapor by a closed or partly closed evaporation control valve or a check valve in the tank vapor line”, means that all or in substance all HTF flows in the direction during charge: vapor line, ec-TES, liquid line, ST, and if open, further flow of vapor through the tank vapor line and into the ec-TES for further condensing until a pressure-temperature balance between the ec-TES and the ST is reached.
Preferably, discharging is controlled by the evaporator control valve in order to maintain an above saturation condition, to prevent liquid reaching the vapor end of the ec-TES.
Preferably, charging takes place with the evaporation control valve closed, whereby all or most of the vapor condensed in the ec-TES is accumulated as liquid in the ST by natural processes. Alternatively, charging takes place with the evaporation control valve open with a check valve installed in the tank vapor line, to enable natural circulation and thus enhance the heat balancing between the ec-TES and the ST.
The invention also provides use of the thermal energy battery of the invention, for storing thermal energy from a source and delivering thermal energy to a recipient.
A deeper understanding of the present invention is achievable by studying the detailed description and the illustrated embodiments.
Brief description of drawings
Figures 1 and 2 illustrate preferred embodiments of the invention.
Detailed description of the invention
Reference is made to Figure 1, illustrating a thermal energy battery of the invention and preferable methods for operation thereof, with steam/water as heat transfer fluid. CV means control valve, controlled based on pressure, temperature, flow or level, as described below.
○ Charge:
○ CV1 controls the flow rate of steam
○ CV2 and CV7 are closed
○ CV3 controls water spray from HP (high pressure) condensate to reduce steam temperature to carbon steel limitation, if needed
○ CV4 controls the flow velocity in the superheater TES below a maximum limit to prevent Flow Accelerated Corrosion (FAC)
○ CV5 is 100% open
○ CV6 (evaporation control valve) is closed if a check valve is not included, or open if a check valve is included
○ Discharge:
○ CV2, CV4 and CV5 operate simultaneously to control both the flow rate and the temperature of the outlet steam flow
○ CV1, CV3 and CV7 are closed
○ CV6 (evaporation control valve) controls T2 to be a few degrees (example given, but not limited to, 10-20 <○>C) higher than saturation temperature. The purpose is to make sure that no condensate will reach the outlet of the ec-TES
○ Stop:
○ CV7 will drain remaining water in the system (the ST is preferably located at the lowest elevation of the ec-TES). Some small amount of water may not be evaporated and discharged due to heat losses in the system, especially after a long idle time
A further thermal energy battery explanation is as follows:
○ Charge:
○ Steam is de-superheated in superheater TES and condensed in ec-TES.
○ For high flow rate, the frictional pressure loss is higher than the hydrostatic pressure, p2 > p3. Any uncondensed steam will be separated in the ST and contribute to pressure build-up.
○ Pressure build-up increases the condensation rate in the ec-TES due to larger delta temperature between the sensible storage material and saturation.
○ When the flow rate is reduced, or the condensation rate is high, the further process is dependent on the check valve:
○ A system without a check valve in the tank vapor line: All the steam will be condensed and sub-cooled in the ec-TES. The sub-cooled water enters the ST and mixes with the saturated water. In this way the colder temperature in the ec-TES is transferred to the higher temperature in the ST, and the temperatures become equal over time.
○ A system with a check valve in the tank vapor line: The hydrostatic pressure becomes higher than the frictional pressure loss, p2 < p3, and steam is recycled through the check valve and further condensed. Such natural circulation continues until the sensible storage material of the ec-TES and the saturation temperature are equal, and the pressure stabilizes. This process of equalization of temperatures is faster than the above described process with no check valve.
○ The storage is fully charged when the pressure reaches the maximum operating pressure.
Discharge:
○ The storage is depressurized by discharging low pressure steam, preferably controlled by CV2 and CV5
○ Initially, steam from the pressure vessel is released by opening CV6 (evaporation control valve). This results in a larger temperature difference between the sensible storage material and condensate, furthermore CV6 controls the amount of steam going directly to the superheater TES and the amount of condensate through the ec-TES.
○ The steam volume in the ST will expand and push the condensate through the ec-TES.
○ If some condensate gets closer to the steam end of the ec-TES, the T2 temperature will be reduced. Then steam is released through CV6, and the two-phase condensate/steam region is stabilized some distance below the steam end of the ec-TES.
○ The outlet steam flow rate and temperature are preferably controlled by CV2, CV4 and CV5. Due to a high temperature drop of a control valve with a high pressure drop, the outlet temperature can be controlled by CV2 and CV5 within a given range. The bypass valve CV4 can expand this range to lower temperatures. By controlling the outlet temperature, a constant temperature can be provided to the heat consumers during the entire discharge cycle, even though the temperature of the sensible storage material in the superheater TES is reduced.
○ The discharge steam flow will stop when the storage is fully discharged due to low pressure. Valve CV2 and CV5 is fully open, and the flow rate drops below the target value.
The thermal energy battery of the invention can for example be integrated into a CCPP, a combined cycle power plant. The HP inlet can be coupled to receive HP steam from upstream a HP turbine. The LP outlet can be coupled to deliver LP steam to a LP turbine. HP (high or higher pressure) and LP (low or lower pressure) are relative to each other. HP is typically 30 – 180 bar. LP is typically 1 to 20 – 40 bar. The HP temperature is typically 150 – 420 °C. The ec-TES and ST operating temperature is typical at 150 – 300 °C.
Any source of HP steam can be used, and any source of LP steam can be connected, or any feasible vapor-liquid, in principle.
In the thermal energy battery of the invention, no pump or compressor is required for flow. The pressure drives the flow between HP inlet and LP outlet. The HP inlet and the LP outlet are in many embodiments, where either charging or discharging is acceptable, the same structure.
The lower end of the thermal energy battery is closed during all operation of charging and discharging, hence no liquid enters or exits the thermal energy battery during normal operation. The vapor or steam do enter the battery in one end and leave the battery in the same end; the thermal energy battery vapor end. During charging and discharging, the ec-TES, and the ST, in substance follows each other with respect to temperature, up or down, respectively. During charging, either due to the check valve or the closed evaporation control valve, the steam flows into the ec-TES and not into the ST. During charging, the steam/condensate flows counterclockwise (related to the illustration, not literally) into the ec-TES and then into the ST. The check valve enables recycled steam from the ST to mix with the steam from the heat source by the process of natural circulation. Without a check valve and with an open evaporation control valve, recycling of steam by natural circulation in the same direction as described above is possible only when there is no (or minor) charge flow from the heat source.
A feasibility study has been completed, with a thermal battery of the invention with steam integrated into a CCPP. The thermal energy battery was operated from 5-75 bar, storing 154 MWh in total, where 34% of the thermal energy was stored in the ST, and 66% of the thermal energy was stored in the ec-TES and the superheater TES. The findings are full storage of all the dumped steam during shut down and startup, and the flexibility of the plant is increased significantly. This eliminates fuel consumption of an auxiliary boiler and enables renewable energy on the power grid.
The battery allows a very high variation in charge flow rates. For the highest flow rates, two-phase steam/water may exit the liquid end of the ec-TES, however, the steam and water are separated in the ST. It may also be necessary to bypass some of the steam directly into the ST, to limit the flow velocity in the ec-TES below a maximum value defined for two-phase flow. The heat from the un-condensed steam in the ST can be transferred to the ec-TES after the charge flow rate is completed, by opening the evaporation control valve and enable natural circulation. The thermal energy battery of the invention, with a combination of high-pressure vessels and solid-state thermal energy storages, operated together with control valves as described and illustrated, enables this high variation in operational flow rates, because no condensate is returned from the system during the charge operation. This design with the combination of superheater modules (superheater TES) and evaporator/condenser modules (ec-TES) and the pressure vessel(s) (ST) has several benefits:
• High flexibility of operation. A high variation in flow rate is accepted for the reasons described above.
• High energy efficiency: The energy density in the pressure vessels is high, and no hot water is wasted in the thermal energy battery. The highquality energy (evaporation and superheating) is mainly stored in the modules.
• High cost efficiency: The combination of modules and pressure vessels minimizes the size of the thermal energy battery. In the pressure vessels, part of the steam is evaporated in the vessel itself, like a steam accumulator, whereas the majority is evaporated by draining the vessel into the evaporator modules. In this way the entire volume of the pressure vessel is actively used, and the modules is used only for evaporation of the vessel drainage and superheating the steam. This combination minimizes the thermal energy battery size and the CAPEX.
• Easy control of evaporation rate during discharge with a single valve controlling the flashing of steam in the pressure vessel and the condensate drainage through the evaporator modules.
• High discharge temperature: The superheater modules can be designed to provide the required temperature for the steam consumers (limited by the maximum temperature for carbon steel)
In summary, the thermal energy battery of the invention, with a combination of high-pressure vessels (ST) and solid-state thermal energy storages represents an inventive solution based on the following:
The slow dynamics of the solid-state TES is overcome by the ST, as this can accumulate all the energy not transferred to the solid-state material in the ec-TES and allow a re-distribution of this energy via natural circulation. Moreover, the inefficiency of using the vessel as a steam accumulator is overcome by allowing the full drainage of the otherwise “dead volume” of liquid and supplying this liquid as “feedwater” for the evaporation of liquid to vapor in the ec-TES. A solid-state storage can further superheat all the vapor in cases where superheated vapor is required and/or beneficial. Hence the combined solution overcomes the main challenges of both technologies separately, while harvesting the main benefits of both, thus providing the most cost-effective solution for storage of thermal energy in two-phase liquid-vapor systems.
The superheater TES, as well as the ec-TES, are preferably according to the design of the Applicant, as described and illustrated in the patent publications WO 2015/093980 A1, WO 2016/099289 A1 and WO 2016/099290 A1, all of which are hereby incorporated in their entirety by reference. However, also other sensible heat thermal storages/batteries can be feasible.
Further reference is made to Figure 2, illustrating an embodiment of a thermal energy battery of the invention without superheater TES, feasible for sources without superheated vapor. The embodiment is in principle identical with the embodiment of Fig.1, except that no superheater, and optionally no check valve, are included. The flow control component corresponds to CV5, and evaporation control valve corresponds to CV6.

Claims (14)

Claims
1.
Thermal energy battery (1), c h a r a c t e r i s e d i n that the thermal energy battery (1) comprises:
an evaporator-condenser thermal energy storage (ec-TES)(Evaporator storage, Evaporator-condenser storage), with an end for vapor and an end for liquid, comprising one-phase stationary material storing at least 70% of the thermal energy stored within the ec-TES,
a storage tank (Storage tank) for vapor and liquid (ST), with a vapor part at a higher elevation and a liquid part at a lower elevation,
a vapor line (evaporator vapor line), arranged to the vapor end of the ec-TES, for inlet and outlet of vapor,
a liquid line (evaporator liquid line, Tank liquid line) arranged between the liquid end of the ec-TES and the liquid part of the ST,
a tank vapor line (Tank vapor line) arranged from the vapor part of the ST to the vapor line, and
an evaporation control valve (CV6) in the tank vapor line.
2.
Thermal energy battery (1) according to claim 1, further comprising one or both of:
a check valve (Check valve) in the tank vapor line, open for flow in direction from the ST and closed for flow in the opposite direction, and
a flow control component (CV5, Flow control component) in the vapor line between a vapor source/recipient and the connection point of the vapor line and the tank vapor line.
3.
Thermal energy battery (1) according to claim 1, further comprising a superheater thermal energy storage (Superheater storage)(superheater TES), comprising one-phase stationary material storing at least 70% of the thermal energy stored within the superheater TES, arranged inline or to the vapor line between sources/recipients and the connection point of the vapor line and the tank vapor line.
4.
Thermal energy battery (1) according to claim 1, wherein the vapor line, towards a source/recipient, comprises a separate inlet vapor line and a separate outlet vapor line, wherein each of said vapor lines include a flow control component (CV1, CV2).
5.
Thermal energy battery (1) according to claim 1, further comprising:
for embodiments with superheater TES, a superheater bypass line with a valve (CV4), arranged so as to bypass part or all the vapor flow through the superheater TES arranged inline to the vapor line;
for embodiments with superheater TES, a valve (CV5) in the vapor line between the superheater TES and the connection point of the vapor line and the tank vapor line;
a valve (CV1) arranged in the vapor line, controlling a supply of HP (high pressure) vapor to an inlet;
a valve (CV2) arranged in the vapor line, controlling the delivery of LP (low pressure) vapor from an outlet;
a line with a valve (CV3) for injecting HP condensate to the vapor line, for temperature control to avoid overheating, between source and superheater TES, or for embodiments with no superheater TES, between the source and the connection point of the vapor line and the tank vapor line; and
a drainage line with a valve (CV7), arranged from the liquid line.
6.
Thermal energy battery (1) according to claim 1, wherein the ec-TES, and the superheater TES if present, consists of solid-state material and are solid-state material sensible thermal energy storages.
7.
Thermal energy battery (1) according to claim 1, wherein the ST, at least the liquid part thereof, is located at an equal elevation or a lower elevation than the liquid end of the ec-TES, preferably arranged either horizontally or as several vertical tanks in parallel.
8.
Thermal energy battery (1) according to claim 1, further comprising: electric resistive heating elements inside the ST for charging with electric power;
preferably further comprising a liquid line to the liquid part of the ST, for supply of liquid during charge;
for embodiments with superheater TES, an electric superheater arranged in a line from the vapor part of the ST to the vapor line between the vapor recipient and the superheater TES.
9.
Thermal energy battery (1) according to claim 6, wherein the ec-TES, and the superheater TES if present, comprises numerous closely arranged concrete thermal energy storage elements with pipe heat exchangers fully embedded in the concrete between a pipe heat exchanger inlet and a pipe heat exchanger outlet in the same end or part of the element, an outer shell, preferably a metal shell, being a concrete casting form, ring armoring and fluid leakage confiner, wherein the elements are horizontally oriented but vertically stacked, wherein the ec-TES vapor line is at a higher or highest elevation and ec-TES liquid line is at a lower or lowest elevation.
10.
Method of operating a thermal energy storage battery (1) according to claim 1 – 9, c h a r a c t e r i s e d b y the steps:
charging by supplying HP vapor, higher pressure vapor, from a source through the vapor line, with the tank vapor line closed or partly closed for the vapor by a closed or partly closed evaporation control valve or a check valve in the tank vapor line, until a maximum or desired pressure and temperature are reached, and
discharging LP vapor, lower pressure vapor, to a recipient through the vapor line, controllable at least by the evaporation control valve, until a minimum or desired temperature and pressure is reached.
11.
Method according to claim 10, whereby discharging is controlled by the evaporation control valve by maintaining an above saturation condition, to prevent liquid reaching the vapor end of the ec-TES.
12.
Method according to claim 10, whereby charging takes place with the evaporation control valve closed, whereby all or most of the vapor condensed in the ec-TES is accumulated as liquid in the ST by natural processes.
13.
Method according to claim 10, whereby charging takes place with the evaporation control valve open and a check valve installed in the tank vapor line, whereby all or most of the vapor condensed in the ec-TES is accumulated as liquid in the ST by natural processes.
14.
Use of a thermal energy battery according to any of claim 1-9, for storing thermal energy from a source and delivering thermal energy to a recipient.
NO20190853A 2019-06-12 2019-07-05 Thermal energy battery NO345513B1 (en)

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NO20190853A NO345513B1 (en) 2019-07-05 2019-07-05 Thermal energy battery
AU2020292109A AU2020292109A1 (en) 2019-06-12 2020-06-12 Thermal energy battery
EP20821624.2A EP3983744A4 (en) 2019-06-12 2020-06-12 Thermal energy battery
MA056210A MA56210A (en) 2019-06-12 2020-06-12 THERMAL ENERGY BATTERY
US17/612,494 US11709024B2 (en) 2019-06-12 2020-06-12 Thermal energy battery
CN202080042115.0A CN113994167B (en) 2019-06-12 2020-06-12 Thermal energy battery
PCT/NO2020/050159 WO2020251373A1 (en) 2019-06-12 2020-06-12 Thermal energy battery

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US20110162400A1 (en) * 2010-07-19 2011-07-07 Daniel Reich Modular Evaporator and Thermal Energy Storage System for Chillers
DE102014216597A1 (en) * 2014-08-21 2016-02-25 Deutsches Zentrum für Luft- und Raumfahrt e.V. A heat storage device and method of operating a heat storage device
US20180292097A1 (en) * 2015-12-12 2018-10-11 Micro-Utilities, Inc. Passive energy storage systems and related methods
WO2019038292A1 (en) * 2017-08-22 2019-02-28 Technische Universiteit Eindhoven Closed cycle thermal energy storage system using thermochemical material

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* Cited by examiner, † Cited by third party
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US20080022713A1 (en) * 2006-07-26 2008-01-31 Jacobi Robert W Thermal storage unit for air conditioning applications
US20110162400A1 (en) * 2010-07-19 2011-07-07 Daniel Reich Modular Evaporator and Thermal Energy Storage System for Chillers
DE102014216597A1 (en) * 2014-08-21 2016-02-25 Deutsches Zentrum für Luft- und Raumfahrt e.V. A heat storage device and method of operating a heat storage device
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WO2019038292A1 (en) * 2017-08-22 2019-02-28 Technische Universiteit Eindhoven Closed cycle thermal energy storage system using thermochemical material

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