Green energy thermal storage system

Abstract

We provide an environmentally friendly, "green" thermal energy storage system. [Solution] The thermal energy storage system includes one or more containment vessels, each comprising an internal cavity containing a bed of phase-change material (PCM) capable of storing thermal energy, an array of heaters embedded in the molten phase-change material, and a tube bundle. The heaters are electrically connected to a power source and can heat the PCM to a molten state. The tube bundle comprises heat exchanger tubes embedded in the molten PCM and is configured to transport a working fluid (e.g., water) through the tube side of the heat exchanger tubes. The tubes can be arranged in a plurality of individual tube cartridges, each insertable into and removable from the vessel. During operation, the working fluid is heated by absorbing the thermal energy stored from the molten phase-change material. The PCM is heated by energy extracted from the power grid during off-peak hours.

Description

Technical Field

[0001] [Cross - References to Related Applications] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 297,899, filed on January 10, 2022, and U.S. Provisional Patent Application No. 63 / 209,234, filed on June 10, 2021. All of the foregoing applications are hereby incorporated by reference into this document in their entirety.

[0002] [Technical Field] The present invention relates to an energy storage system, and more particularly, to a system that utilizes an endothermic phase - change material (PCM) that operates to store thermal energy from electric power absorbed from a power grid or other power sources, and produces hot water for district heating or other purposes, or steam for power generation by a Rankine cycle during peak load demand periods of the power grid.

Background Art

[0003] As the conversion from traditional energy generation to pollution - free "green" energy accelerates, hundreds of thousands of fossil - fuel power plants (especially coal - fired power plants) around the world are heading towards early shutdown and decommissioning. In fact, supported by the new consensus on economic decarbonization and in favor of more environmentally friendly pollution - free "green" alternative power generation, the process of phasing out old fossil - fuel power plants has already begun. Although other facilities of the conventional steam - power Rankine power generation cycle shown in Figure 1A other than fossil - fuel boilers (i.e., steam generators) often remain fully functional and can continue to operate, the resulting destruction and waste of capital assets are estimated to be in the trillions of dollars.

[0004] Another result of the increase in green renewable energy is the greater variation (high and low) in power generation levels. Therefore, an energy storage system is needed to smooth the power supplied to the power grid by such green power generation systems.

Summary of the Invention

[0005] This disclosure provides an environmentally friendly "green" thermal energy storage system that provides its stored thermal energy when needed to heat a heat transfer working fluid. The working fluid may be water or a water mixture in some embodiments and applications, but other types of working fluids may be used in other applications. The system includes one or more thermal energy storage vessels, each containing a bed of phase change material (PCM) that absorbs and stores heat obtained from a power source. The PCM heats the working fluid flowing through the vessels as required for various purposes.

[0006] In some embodiments, the thermal energy storage system of the present invention may be used to heat water for district heating or other applications. In other embodiments, the thermal energy storage system may be used to generate steam for generating electricity. In any of these applications, as further described herein, electricity is preferably drawn from a power source such as a power grid to heat the PCM in the container during off-peak load demand periods of the power grid when energy prices are low, but these thermal energy systems may draw electricity from a power source during other periods, including peak load demand periods, as needed. Therefore, the timing of drawing electricity from a power grid or other storage source and storing it as thermal energy is not limited to a specific period.

[0007] In the latter application described above, the technology disclosed herein replaces the conventional fossil fuel boiler portion of the Rankine power cycle with a "green boiler" that functions as both an energy storage device and a corresponding "on-demand" steam generator / power generator without consuming fossil fuels. This would significantly reduce the enormous capital investment required for fossil fuel power plants and fully contribute to the achievement of humanity's energy decarbonization goals.

[0008] The green thermal energy storage and generation system described herein provides a means of matching power output to the fluctuating load demands of the power grid, and the system can be retrofitted to existing fossil fuel power plants and can be operated to provide steam and electricity as needed while eliminating the use of fossil fuels at the power plant; therefore, it is referred to herein as a “green boiler.” The turbogenerator and the Rankine cycle equipment infrastructure remaining in conventional fossil fuel-burning power plants are maintained, and only the components of the fossil fuel boiler and its associated subsystems are removed and replaced.

[0009] Therefore, the green boiler technology disclosed herein envisions replacing existing fossil fuel-burning boilers in power plants with “green boiler systems,” transforming power plants into both energy storage facilities and clean power generation facilities. In some embodiments, the green boiler system may also be a standalone energy storage device that receives input energy from associated solar, wind, or nuclear power plants.

[0010] The current "green boiler" concept relies on the fact that for most of the 24 hours of the day, the electricity supplied from power plants to the grid exceeds the actual real-time electricity demand of consumers (industrial, commercial, residential, etc.). In other words, there are times when inexpensive surplus electricity is unfortunately wasted. A green boiler takes in surplus energy from the grid, or alternatively, directly from an adjacent green energy power plant (solar, wind, nuclear, etc.), and in one embodiment, but not limited to, heat-stores the energy in a phase-change material (PCM), such as a molten salt bed.

[0011] Regarding power generation, the PCM Green Boiler is configured and functions to boil and superheat the boiler feedwater for the Rankine power generation cycle and produce electricity "on demand" whenever the power grid faces a power shortage to meet current demand. Therefore, when the power grid faces a power shortage, the Green Boiler can act as an additional peak power generation unit, replacing conventional small natural gas or diesel peak power generation units used during periods of power load fluctuations in the power grid. In other words, the Green Boiler is activated when electricity demand exceeds the supply capacity from the power grid's baseload units. Thus, conventional large "baseload" polluting fossil fuel power plants with fossil fuel boilers are converted into on-demand clean energy generators that play the role of peak power generation.

[0012] From a sociological standpoint, the reorganized power plants will have little impact on the host communities, as they will retain the employment of workers (after some retraining). However, the sources of hydrocarbon emissions will be advantageously eliminated. Furthermore, in coal-fired power plants, residual fly ash and bottom ash resulting from burning coal in the boilers will also be eliminated. Some coal-fired power plants use wet chute drainage as a method of ash treatment, thus removing suspended solids, heavy metals, or other components contained in the ash from such waste vapors, and reducing the costs associated with wastewater treatment and purification to meet regulatory emission limits.

[0013] In principle, converting environmentally unclean boilers to green boiler technology can be applied without exception to any fossil fuel plant worldwide. Therefore, the decarbonization of the power generation economy can be implemented without delay and with maximum efficiency. Scoping calculations show that the conversion to green boilers is by far the cheapest route in terms of capital costs for decarbonizing existing fossil fuel-burning power plants. Operating costs are similarly lower than any other energy storage and supply technology.

[0014] Replacing existing fossil fuel / coal-burning boilers, oil-burning boilers, or natural gas-burning boilers with “green boilers” consisting of assemblies of fluidly interconnected and heated phase-change material (PCM) containment vessels, each of which stores thermal energy in molten salt, is a non-limiting aspect of the innovative green energy storage and power generation systems disclosed herein.

[0015] Each molten salt PCM containment vessel is configured and operational to heat and melt the solid salt particles it contains using electricity extracted from the power grid (or an adjacent clean energy power plant) via a salt stock or an array of heating elements embedded in the bed, when the available power supplied to the power grid exceeds demand. Each PCM containment vessel includes a tube bundle containing multiple heat exchanger tubes, which are fluidly isolated from the molten salt bed, to transport and flow the boiler feedwater of the Rankine cycle through the vessel on the internal tube side of the vessel. On the shell side of the vessel (outside the tubes within each vessel), there is molten salt in close, direct contact with the outside of the tubes. During operation of the power grid to which the Green Boiler Rankine cycle generators are electrically connected, the Green Boiler uses the thermal energy stored in the molten salt to heat the boiler feedwater in a cascaded salt bed with progressively higher melting points contained in the heat exchanger vessel, generating steam. The steam is supplied to a steam turbine, which drives the steam turbine. Steam turbines generate electricity "on demand" during peak load periods in the power grid by rotating generators that are mechanically coupled to the steam turbine in known ways.

[0016] In one embodiment, the molten salt PCM containment vessel of the green boiler system may be elongated and have fluid communication on the water side, and may include an optional preheater to preheat the boiler feedwater (still in the liquid phase), a boiler that heats the water to convert it into wet (i.e., saturated) steam, and a superheater that dries (i.e. removes moisture from) the steam to a superheated state supplied to the steam turbine. The preheater can be omitted if the incoming boiler feedwater is sufficiently hot. Upstream of the steam turbine, some embodiments include a steam recovery vessel that receives and recovers superheated steam directly from the superheater vessel. All of the aforementioned vessels are preferably tightly insulated for heat retention and may be housed together in a common enclosure structure or housing. In one embodiment, the vessels are elongated vertically and can be mounted on a sloped or elevated reinforced concrete support pad.

[0017] It is noteworthy that in fossil fuel boiler refurbishment and replacement programs, the enthalpy of the superheated steam in the green boiler system is set to a size that matches the design standard steam volume of the fossil fuel boiler being replaced. Therefore, since there is no change in the thermal load of the equipment, it can be used without changing the balance of the equipment at the power plant.

[0018] In district heating applications, one or more heated PCM containment vessels, similar in structure to those described above, can utilize the thermal energy stored in a molten salt bed to heat and generate hot water, which can then be pumped up and distributed to local municipalities to heat buildings. The water is heated to approximately 93°C (approximately 200°F) and kept saturated but not boiling for heating purposes. Multiple heated molten salt containment vessels may be arranged in parallel and fluidly coupled to supply the total amount of hot water required for district heating. An advantage is that a modular system can be provided that allows for the addition of PCM containment vessels as the demand for district heating increases with population and infrastructure growth.

[0019] In one embodiment, the thermal energy storage vessel comprises: an elongated body defining an internal cavity containing a bed of phase-change material operable to store thermal energy; an array of heaters embedded in the phase-change material, the heaters configured to be electrically coupled to a power source and operable to heat the phase-change material to melt it into a molten state; and a tube bundle comprising a plurality of heat exchanger tubes embedded in the molten phase-change material, the heat exchanger tubes configured to transport a working fluid through the heat exchanger tubes to absorb thermal energy from the molten phase-change material. The phase-change material may be a salt, and the working fluid may consist of water alone or a mixture of water (e.g., water and glycol).

[0020] In another embodiment, the thermal energy storage and power generation system comprises a steam turbine, a steam condenser, a boiler assembly, and a closed flow loop through which a pump operable to circulate boiler feedwater is fluidly connected; a generator operable to the steam turbine and the power grid; and a boiler assembly comprising a thermal energy boiler vessel and a thermal energy superheater vessel fluidly connected to the boiler vessel, each vessel comprising an elongated tubular body defining an internal cavity containing a bed of molten phase change material operable to store thermal energy, and an array of heaters embedded in the molten phase change material, electrically connected to the power grid. The system comprises a boiler assembly comprising an array of heaters combined and energized to heat a molten phase-change material, and a tube bundle consisting of a plurality of heat exchanger tubes embedded in the molten phase-change material, the heat exchanger tubes configured to transport boiler feedwater through the tube sides of the heat exchanger tubes, wherein the thermal energy boiler vessel is configured to receive feedwater in a liquid state which is heated by the molten phase-change material within it to produce saturated steam, and the thermal energy superheater vessel is configured to receive saturated steam which is heated to a superheated state by the molten phase-change material within it, and the superheated steam flows through a steam turbine which rotates a generator to produce electricity. In some embodiments, the system further comprises a thermal energy preheater vessel which is fluidically coupled to a closed flow loop upstream of the boiler vessel. The preheater vessel may be configured and have the same characteristics as the boiler vessel and the superheater vessel. The phase-change material may be a salt, and different types of salt may be used in each vessel.

[0021] In another aspect, a method of heating a working fluid includes providing a thermal energy storage vessel that includes an internal cavity containing a bed of a solid-state phase change material and a tube bundle including a plurality of tubes embedded in the bed of the phase change material, energizing a plurality of heating elements embedded in the bed of the phase change material to heat and transform the phase change material from a solid state to a molten state, and flowing the working fluid through the molten phase change material that heats the working fluid at a first temperature to a higher second temperature. The phase change material may be a salt, and the working fluid may include water alone or a water mixture (e.g., water and glycol). In some embodiments, the water enters the thermal energy storage vessel in a liquid state and is heated by the phase change material from the first temperature to a higher second temperature in the liquid state. In another embodiment, the water entering the vessel is in a liquid state and is heated by the phase change material to convert the water to steam. In yet another embodiment, the water is saturated steam entering the thermal energy storage vessel and is heated by the phase change material to superheated steam.

Brief Description of the Drawings

[0022] Features of exemplary embodiments of the present invention will be described with reference to the following drawings, wherein like elements are denoted by like reference numerals.

[0023] [Figure 1A] FIG. 1A is a schematic diagram of a conventional Rankine power generation cycle system that uses a fossil fuel boiler that pollutes to generate steam.

[0024] [Figure 1B] FIG. 1B is a schematic diagram of a Rankine power generation cycle system according to the present disclosure, including a pollution-free thermal energy storage green boiler according to the present disclosure for generating steam for the cycle.

[0025] [Figure 2] FIG. 2 is a perspective view of a green boiler including a set of thermal energy storage vessels according to the present disclosure.

[0026] [Figure 3]Figure 3 is a partial perspective view of the upper part of one of the thermal energy storage containers of Figure 2.

[0027] [Figure 4] Figure 4 is a partial perspective view of its lower part.

[0028] [Figure 5] Figure 5 is a partial perspective view similar to Figure 3, but also shows the upper opening / closing lid of the container in cross-section.

[0029] [Figure 6] Figure 6 is a top perspective view showing the upper part of the tube bundle of the container.

[0030] [Figure 7] Figure 7 is a top perspective view of the lower part of the tube bundle.

[0031] [Figure 8] Figure 8 is a bottom perspective view of the upper part of the tube bundle.

[0032] [Figure 9] Figure 9 is a bottom perspective view of the lower part of the tube bundle.

[0033] [Figure 10] Figure 10 is a side view of the thermal energy storage container.

[0034] [Figure 11] Figure 11 is a top view thereof.

[0035] [Figure 12] Figure 12 is a bottom view thereof.

[0036] [Figure 13] Figure 13 is a longitudinal / longitudinal cross-sectional view thereof as seen from Figure 10.

[0037] [Figure 14]Figure 14 is an enlarged view of Figure 13.

[0038] [Figure 15] Figure 15 is a cross-sectional view taken from Figure 13.

[0039] [Figure 16] Figure 16 is a top perspective view of a first embodiment of a heat exchanger tube cartridge in a tube bundle configured for a 6-pass tube-side flow of working fluid through a container.

[0040] [Figure 17] Figure 17 is a perspective view of its lower surface.

[0041] [Figure 18] Figure 18 is its first side view.

[0042] [Figure 19] Figure 19 is a second side view thereof.

[0043] [Figure 20] Figure 20 is a cross-sectional view in the longitudinal direction as seen from Figure 18.

[0044] [Figure 21] Figure 21 is a top view thereof.

[0045] [Figure 22] Figure 22 is a view from below.

[0046] [Figure 23] Figure 23 is a top perspective view of a second embodiment of a heat exchanger tube cartridge of a tube bundle configured for a three-pass tube-side flow of working fluid through a container.

[0047] [Figure 24] Figure 24 is a perspective view of its lower surface.

[0048] [Figure 25] Figure 25 is its first side view.

[0049] [Figure 26] Figure 26 is a second side view thereof.

[0050] [Figure 27] Figure 27 is a perspective view showing the working fluid flow path on the tube side through the tube cartridge.

[0051] [Figure 28] Figure 28 is a longitudinal cross-sectional view thereof.

[0052] [Figure 29] Figure 29 is a top view thereof.

[0053] [Figure 30] Figure 30 is a view from below.

[0054] [Figure 31] Figure 31 is a top perspective view of a third embodiment of a heat exchanger tube cartridge of a tube bundle configured for single-pass tube-side flow of working fluid through a container.

[0055] [Figure 32] Figure 32 is a perspective view of its lower surface.

[0056] [Figure 33] Figure 33 is its first side view.

[0057] [Figure 34] Figure 34 is a second side view thereof.

[0058] [Figure 35] Figure 35 is a longitudinal cross-sectional view thereof.

[0059] [Figure 36]Figure 36 is a top view thereof.

[0060] [Figure 37] Figure 30 is a view from below.

[0061] All drawings are schematic and not necessarily to scale. A part designated by a reference number in one drawing may be considered the same part as a part shown without a number in another drawing, unless otherwise described herein and labeled with a different part number. In this specification, a reference to a serial number consisting of multiple drawings with the same serial number but different alphabetical suffixes shall be interpreted as a general reference to all drawings sharing the same serial number, unless otherwise indicated. [Modes for carrying out the invention]

[0062] Features and advantages of the present invention are illustrated and described herein by reference to exemplary ("Example") embodiments. The description of these exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are considered to be part of this whole specification. Accordingly, this disclosure should not be particularly limited to such exemplary embodiments which describe some possible non-limiting combinations of features that may exist individually or in combination with other features.

[0063] In the description of embodiments disclosed herein, references to directions or orientations are intended solely for explanatory convenience and are not intended to limit the scope of the invention. Relative terms such as “down,” “up,” “horizontal,” “vertical,” “upward,” “downward,” “up,” “down,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the orientation being described at that time or the orientation shown in the drawings discussed. These relative terms are for explanatory convenience only and do not require that the device be constructed or operated in a particular direction. Terms such as “attached,” “attached,” “connected,” “joined,” and “interconnected” refer to relationships in which structures are fixed or attached to one another directly or indirectly via intervening structures, and both movable and fixed attachments or relationships, unless expressly stated otherwise.

[0064] As used throughout, the terms "scope" disclosed herein are used as descriptive abbreviations for each value within the scope. Any value within the scope may be selected as the boundary of the scope. Furthermore, all prior art referenced herein in relation to prior art or patent applications are incorporated herein by reference in their entirety. In the event of any discrepancy between the definitions in this disclosure and those in the referenced art, this disclosure shall prevail.

[0065] Figure 1A shows a conventional Rankine power generation cycle with a large fossil fuel boiler for generating the steam necessary for power generation. The basic cycle equipment (excluding auxiliary systems) includes, as shown, a fossil fuel-fired boiler (coal, oil, natural gas, etc.), a steam turbine generator set, a condenser that condenses the steam discharged from the steam turbine back into a liquid, and a boiler feedwater pump that circulates the boiler feedwater (heat-exchange working fluid) taken from the condenser through a closed flow loop formed by piping that fluidly connects each component. The generator is mechanically coupled to the steam turbine and electrically coupled to the power grid (represented by the transmission towers shown). It is known that the steam generated in the boiler rotates the turbine shaft via a row of turbine blades, which in turn rotates the generator rotor in the stator (magnet), converting mechanical energy into electrical energy. The Rankine cycle power generation system and its power generation operation are well known to those skilled in the art and do not require further detail.

[0066] Rankine system fossil fuel boilers (steam generators) that convert liquid boiler feedwater into steam have traditionally been used for base load operation to meet the base load demand of the power grid, because such boilers and associated auxiliary equipment cannot be started immediately for on-demand power generation. In fact, the entire start-up process for fossil fuel base load plants takes many hours to bring all equipment up to the operating conditions of full pressure and temperature required to reach full load.

[0067] Figure 1B shows a clean energy "green" Rankine power generation cycle system, including a steam generator featuring the pollution-free "green boiler" technology described herein. The green boiler replaces the fossil fuel steam boiler of Figure 1A with a thermal energy containment vessel configured as both a containment vessel and a heat exchanger of a phase-change material (PCM), as further described herein. In one embodiment, the PCM is a molten salt.

[0068] This thermal energy storage and power generation system 100 can be configured and used as a "peaking" power generation system that generates and supplies power to the power grid during peak load demand. Conversely, the electrical energy extracted from the power grid during "off-peak" load demand periods when there is excess energy in the power grid is used to "charge" the molten salt bed of the green boiler, as already described herein.

[0069] The green thermal energy storage and power generation system 100 shown in Figure 1B may include, but is not limited to, a steam turbine 102, a generator 103 mechanically coupled thereto and operably connected to a power grid 104, a steam condenser 105, a boiler feedwater pump 106, and a thermal energy storage boiler 120 filled with molten salt. The feedwater pump circulates boiler feedwater through a closed flow loop 110 formed by piping that fluidly connects the components receiving water in the Rankine cycle, as shown. Except for this green boiler assembly, the remaining components of the clean energy Rankine cycle operate in the same known manner as in a conventional Rankine cycle and produce electricity.

[0070] For on-demand power generation applications used in the Rankine cycle described above, the thermal energy storage boiler 120 may be an assembly comprising a plurality of fluidically coupled and interconnected thermal energy storage vessels 121. The thermal energy storage vessels may include an optional thermal energy preheater vessel 121A, a thermal energy boiler vessel 121B, and a thermal energy superheater vessel 121C, in order of the working fluid flow. These vessels are piped in a series flow arrangement as shown (see working fluid flow direction arrows). In the illustrated embodiment, the working fluid includes water, which may be boiler feedwater in the Rankine cycle of Figure 1B. In some embodiments, the preheater vessel can be omitted if the feedwater flowing in from the condenser is sufficiently hot. If used, the preheater vessel receives the feedwater in a “cold” liquid state at a first temperature and heats the feedwater to a higher second temperature while it remains in liquid state. The heated feedwater flows into the boiler vessel, where it is further heated and undergoes a phase change from liquid to saturated steam before flowing into the superheater vessel. The superheater vessel heats the saturated steam to a superheated state. The superheated steam flows through the closed flow loop 110 to the steam turbine 102 (Figure 1B), which drives the steam turbine 102, rotating the generator shaft or rotor to generate electricity, which is then supplied to the power grid.

[0071] Since the preheater vessel 121A, boiler vessel 121B, and superheater vessel 121C must receive the working fluid (e.g., water or steam in liquid state) at different temperatures and heat the fluid to different temperatures and conditions, the PCM (phase change material) used in each vessel may differ in at least one property, including, but not limited to, the melting temperature and / or type of the PCM. The PCM may be a salt having properties suitable for the required heat load.

[0072] Referring to Figures 2–15, which can be applied first, each vessel has a similar structure generally comprising a longitudinally oriented, elongated body 123 that indicates a vertical centerline axis CA passing through the geometric center of each vessel. Each vessel body includes a longitudinal internal cavity 122 that extends substantially over the entire height of the vessel (excluding the thickness of the upper and bottom closing structures of the vessel). Each internal cavity includes a bed B of molten salt that is contained within the vessel in a trapped state so that the molten salt does not flow into or out of the containment vessel 121 during boiler operation. Only working fluids, such as boiler feedwater FW, flow through the vessel in a cascaded series configuration, as further described herein.

[0073] The thermal energy storage container body 123 may be cylindrical in one embodiment, as defined by cylindrical vertical side walls 124 that define the internal cavity 122 of the container. Each container includes an upper closure lid 125 coupled to the upper end of the side wall 124, defining the top of the container, and a bottom closure plate 126 coupled to the lower end of the side wall, defining the bottom of the container. The lid 125 and bottom closure plate 126 are sealed to the ends of the side walls, fluidly enclosing the cavity 122 and sealing the molten salt bed without leakage. In one embodiment, the lid 125 and bottom closure plate 126 may be seal-welded to each end of the cylindrical container side wall 124. In another embodiment, the lid 125 may be detachably coupled to the upper end of the container body 123 (e.g., the side wall 124) via a plurality of threaded fasteners such as bolts. Other detachable fastening methods may be used.

[0074] The thermal energy storage vessel 121 is supported by a reinforced concrete pad 135, as shown in the figure, and mounted vertically on top of it. In one embodiment, each vessel may have a plurality of structural legs 129 that raise the bottom of the vessel above the concrete pad. The structural legs may be welded to the lower vessel body 123 and fixed to the concrete pad via a plurality of anchor bolts (not shown) or other suitable means, in particular to ensure stability during earthquakes.

[0075] The cylindrical side wall 124 of the container body 123 may have a composite structure consisting of an innermost shell 130, an outermost shell 131, and an intermediate shell 132 that is positioned close to the outermost shell but radially spaced away from it (see, for example, Figures 13-15). Therefore, the intermediate shell 132 is closer to the outermost shell than the innermost shell. Each shell 130-132 has a hollow tubular cylindrical shape.

[0076] The body 123 of the thermal energy storage container 121, including the shells 130-132, the top closing lid 125, and the bottom closing plate 126, may in one embodiment be formed of a suitable metal such as steel, preferably stainless steel. These parts of the container body may be welded to each other to form a welded assembly, with the exception of the top closing lid 125, which in some embodiments may be detachably coupled to the side walls 124.

[0077] In one embodiment, a vacuum annular body 128 may be provided and formed between the outer shell 131 and the intermediate shell 132. The vacuum annular body is evacuated and sealed to below atmospheric pressure (i.e., negative pressure) or vacuum V, and serves to thermally insulate the heat energy storage vessel 121 within the side wall structure. In one embodiment, the vacuum annular body may be evacuated to about 0.067 kPa (0.5 Torr). Multiple longitudinally spaced annular shell support ribs 134 are installed between the outermost shell 131 and the intermediate shell 132 to prevent the collapse of the vacuum annular body 128 when the interior is exposed to a vacuum. The ribs 134 are formed of a metallic material (e.g., steel or preferably stainless steel) and welded to the shells 131 and 132. In some embodiments, the ribs 134 may be insulated to reduce conductive heat transfer from the vessel cavity 122 to the outermost shell 131.

[0078] In one embodiment, the opposing surfaces of the outermost shell 131 and the intermediate shell 132, which may be formed of stainless steel facing inward toward the vacuum annular body 128, are highly polished to form reflective surfaces for reflecting heat inward and to increase the thermal insulation value of the vacuum annular body.

[0079] To further insulate the thermal energy storage vessel 121, an insulating annular body 127 may be formed between the innermost shell 130 and the intermediate shell 132, as shown in the figure. The insulating annular body 127 has a greater radial width than the vacuum annular body 128 and may contain a suitable insulating material 133. It is worth noting that each of the insulated annular body 127 and the vacuum annular body 128 extends over at least the entire height of the container cavity 122 containing the molten salt bed B, and in some embodiments extends over the entire height of the side wall 124 (see, for example, Figures 13 and 14).

[0080] Each thermal energy storage vessel 121 further comprises a tube bundle 140 containing a number of heat exchanger tubes 141 embedded in but fluidly isolated from the molten salt bed B. Water (including boiler feedwater in the Rankine cycle in Figure 1B) or other types of working fluid flow inside the tubes (inside the tubes) that penetrate each vessel. On the shell side of the vessel (outside the heat exchanger tubes) is the molten salt, which is in close, direct contact with the outside of the heat exchanger tubes for heat transfer. The heat exchanger tubes may extend over 90% or more of the total height of the vessel cavity 122 to maximize the heat transfer surface area of ​​the tube bundle.

[0081] In one embodiment, the heat exchanger tubes 141 of the tube bundle 140 may be separated, arranged, and clustered into a plurality of individual tube cartridges 142, each tube cartridge 142 being removablely insertable into the container 121 through a corresponding complementaryly configured cartridge opening 146 formed in the upper closing lid 125 of the container. Advantageously, the cartridges 142 are replaceable without removing the upper closing lid 125 to access the internal cavity of the container 121, thereby facilitating tube replacement and reducing replacement costs. The tubes of each cartridge may be arranged and configured to allow the working fluid to pass longitudinally in a single or multi-pass manner to absorb heat from the molten salt bed B in the container cavity 122 to heat the working fluid.

[0082] Figures 16–22 depict a first embodiment of the tube cartridge 142 with an illustrative 6-pass tube cartridge 142A, which, as illustrated, is depicted in various configurations installed in the thermal energy storage container 121 of Figures 3–15. As some additional examples, Figures 23–30 depict a 3-pass tube cartridge 142B. Figures 31–37 depict a 1-pass tube cartridge 142C. Any number of tube passes suitable for the intended application can be used to sufficiently heat a working fluid, such as water or another heated in the PCM-containing thermal energy storage container 121, to the desired temperature. Regardless of the number of passes, each tube cartridge 142 shares similar features, which will be described in more detail with respect to the 6-pass tube cartridge 142A.

[0083] Generally referring to Figure 3-22 as appropriate, each tube cartridge 142 (e.g., 142A, 142B, 142C) comprises, in one embodiment, a solid metal cylindrical head 147, including an upper surface 147a and an opposing bottom surface 147b. The head 147 has a thickness substantially equal to that of the upper closure lid 125 of the container (see, for example, Figures 5 and 14). The head 147 is insertable into each circular cartridge opening 146 of the upper closure lid 125 and is coupled to the lid 125 in a fixed fluid-sealing manner, such as by seal welding, to prevent molten PCM or associated vapors from leaking into the ambient atmosphere through the interface between the tube cartridge and the lid. Each tube cartridge 142 may be fully supported by the container lid 125 in a suspended cantilever configuration, as shown, so that no portion of the tube cartridge 142 or the heat exchanger tubes 141 is supported by any portion of the container below the lid. The tube cartridge 142 has an elongated structure in the direction of the hand, as shown in the figure.

[0084] The heat exchanger tubes 141 extend longitudinally and parallel to each other from the tube cartridge head 147 to a metal lower tube support plate 145. The plate 145 may have any suitable shape, such as an annular flat ring as shown in the figure. The upper end of the tube is rigidly attached and coupled to the tube cartridge head 147 and extends through it completely, as best shown in Figure 20. The lower end of the tube 141 extends through the lower tube support plate 145 completely and is rigidly coupled. The tube may be sealed welded to the cartridge head 147 and the lower tube support plate 145. It is worth noting that the lower tube support plate 145 is not fixedly attached to the container body 121 so that it can be slidably removed from the container cavity 122 together with the tube cartridge 142.

[0085] Each tube cartridge 142 further comprises a cartridge fluid inlet 150 for introducing a working fluid such as water (e.g., boiler feedwater) or, in some applications, steam, and a cartridge fluid outlet 151 for discharging the water or steam after heating. The inlet and outlet may be formed by a section of pipe of any suitable configuration having a diameter larger than the diameter of the heat exchanger tube 141. The inlet and outlet are rigidly attached and coupled to the tube cartridge head 147 for support. The inlet 150 is fluid-coupled to a downpipe 152 that extends longitudinally, completely penetrating the tube cartridge head 147, and is coupled to a lower tube support plate 145 (see, for example, Figure 20). In some embodiments, the downpipe may be coupled to the upper surface of the lower tube support plate and sealed welded. Through flow holes (invisible) directly below the downpipe 152 and within the tube support plate 145 inside the tube, the inlet water flow can pass under the plate to redirect to another upflow heat exchanger tube 141.

[0086] Continuing in general terms, we refer to the 6-pass tube cartridge 142A, generally shown in its installed state in Figures 3-15 and specifically shown separated in Figures 16-22. The 6-pass tube cartridge 142A consists of heat exchanger tubes 141 configured such that water passes through a bed of molten PCM (phase change material) multiple times (e.g., six times) as water (or possibly steam) is continuously heated to a high temperature by absorbing heat from the PCM bed. Thus, in any multi-pass tube cartridge, some of the heat exchanger tubes 141 of each tube cartridge may be upward flow tubes and some may be downward flow tubes. The upward flow tubes of each tube cartridge are fluidically coupled to the corresponding downward flow tube members by cross-flow conduits 153, and vice versa to form a multi-pass tube flow arrangement. Multiple cross-flow conduits 153 are sealably attached (e.g., by welding) to the upper surface of the tube cartridge head 147, and the cross-flow conduits 153 are sealably attached to the lower tube support plate 145. The cross-flow conduit reverses the water / steam flow 180 degrees up and down within the tube cartridge 142.

[0087] It should be noted that the cross-flow conduit 153 may be configured to fluidly couple to a single heat exchanger tube 141 or to multiple tubes, depending on the flow path design within the tube cartridge 142. Thus, the cross-flow conduit may divide and distribute the flow from the heat exchanger tube 141 or the fluid inlet 150 to multiple tubes (see, for example, the tee-shaped inlet cross-flow conduit 153a in Figure 24 or Figure 30), or it may couple the flows from multiple heat exchanger tubes into a single flow (see, for example, the tee-shaped outlet cross-flow conduit 153a in Figures 23, 27, or 29).

[0088] Any suitable configuration of the cross-flow conduit 153 can be used, provided that a leak-free fluid coupling is established between the ascending and descending tubes, including, but not limited to, box conduits (153b), circular pipe conduits (153a), or others. Note that the cross-flow conduit 153 may also be used to fluidly couple the fluid inlet 150 and outlet 151 to the corresponding ascending tubes.

[0089] Figures 23-30 show a 3-pass tube cartridge 142B, which is structurally similar to the 6-pass tube cartridge 142A described above. Similar features are given similar labels, as already mentioned. Some differences in configuration / structure include the fact that the lower tube support plate 145 has a solid circular shape, and the descending tube 152 is centrally located, in contrast to being radially offset as in the 6-pass tube cartridge 142A (see, for example, Figure 16).

[0090] Figure 27, showing the 3-pass tube cartridge 142B, includes tube-side fluid flow arrows indicating the path of the working fluid, such as water (in liquid or vapor state), through the tube cartridge 142B as it passes longitudinally through the PCM bed B in the thermal energy storage container 121. It can be seen that the heat exchanger tube 141 functions as both an upward flow tube and a downward flow tube. The same technique is applicable to the 6-pass tube cartridge 142A or any other multi-pass tube cartridge having any other number of passes through the PCM.

[0091] Figures 31-37 depict a single-pass tube cartridge 142C, which is structurally similar to the three-pass tube cartridge 142A and six-pass tube cartridge 142A described above. Similar features are given similar labels, as has already been mentioned. One difference is that the lower tube support plate of the multi-pass tube cartridge is replaced by a lower annular header 148 formed of circular cross-section piping. The centrally located downpipe 152 is in fluid communication with the annular header. The lower ends of the heat exchanger tubes 141 are in direct fluid communication with the annular header 148, as shown in the figure. During operation, the working fluid (e.g., water) flows longitudinally downward through the downpipe 152 and enters the annular header 148, from where the flow is evenly distributed to the heat exchanger tubes. The flow then moves upward through the tubes, forming a single pass within the tubes that passes through the PCM bed B to absorb heat. In one embodiment, the single-pass tube cartridge may include an upper annular header 149 formed by a circular portion of piping that receives working fluid flowing upward from the tube, to which the upper end of the tube is fluidically coupled. The annular header 149 is mounted on the upper surface of the upper head 147 of the tube cartridge, as shown in the figure.

[0092] The tube cartridge 142, regardless of the number of passes, is an entire metallic structure including the head 147 and the lower tube support plate 145. The fluid inlet 150, fluid outlet 151, cross-flow conduit 153, and lower annular header 148 of the single-pass tube cartridge 142C are preferably formed of a suitable metallic material such as steel or stainless steel. Stainless steel is generally preferred and used whenever possible due to its excellent corrosion resistance. The heat exchanger tubes 141 may be made of any suitable material, including stainless steel if possible. The type of tube material can be selected for compatibility with the specific type of PCM material used and for use, so as not to be affected by the corrosive properties of the PCM material. Other metallic materials may be used for any of the aforementioned components.

[0093] Each thermal energy storage container 121 is equipped with a plurality of inlet and outlet headers to distribute the incoming cooling working fluid (for example, water or steam in one embodiment) to the tube cartridge 142, or to collect the heating working fluid flowing out of the tube cartridge. In one embodiment, a metal annular or circular ring header may be provided, including an inlet ring header 160 and an outlet ring header 161, best shown in Figures 3, 5, 6, 8, and 11. The illustrated embodiment includes a pair of inlet ring headers 160 and a pair of outlet ring headers 161. The inlet and outlet ring headers are concentric and aligned with respect to each other. Thus, the ring headers may have different diameters to form the illustrated nested arrangement. Furthermore, the inlet and outlet ring headers may be arranged alternately so that the inlet and outlet ring headers are not adjacent to each other but scattered. One inlet ring header 160 includes a header inlet pipe 162 that receives cooled working fluid for distribution, and one outlet ring header 161 includes a header outlet pipe 163 that discharges heated working fluid collected from the tube cartridge 142. A jumper pipe 164 may be used to fluidically connect two inlet ring headers 160 so that the incoming working fluid is transferred from one ring header to the other. A similar arrangement and jumper pipe 164 may be used to fluidly connect two outlet ring headers 161, as shown in the figure. The number of inlet and outlet ring headers depends on the number and arrangement of the tube cartridges 142. A fluid inlet 150 from each tube cartridge 142 is fluidly connected to one of the inlet ring headers 160. A fluid outlet from each tube cartridge is fluidly connected to one of the outlet ring headers 161.

[0094] In one embodiment, the inlet ring header 160 and outlet ring header 161 of the container may be positioned above and supported by the upper closing lid 125 of the thermal energy storage container 121. In one embodiment, a structural standoff member 165 may be used to raise each ring header upward and support it from the top surface of the lid (schematically shown in Figure 3). Any type of structural member (rod, angle, etc.) may be used. The ring headers 160, 161 are formed of steel or a suitable metal such as preferably stainless steel.

[0095] During operation, the incoming cooling working fluid flow, such as water (liquid or vapor), enters the first inlet ring header 160 from the header inlet pipe 162. A portion of the flow is transferred to the second inlet ring header 160 via one or more jumper pipes 164. In other embodiments, the incoming working fluid may be branched instead of flowing in series and distributed equally to both inlet ring headers simultaneously. The same applies, but with the arrangement and flow scheme of the outlet ring header 161 reversed.

[0096] In either case, the inflow is distributed from each inlet ring header 160 to the tube cartridge 142, where the fluid passes through the PCM bed of the container 121 once or more times and is heated. The heated working fluid (liquid or vapor) is collected from the tube cartridge by a pair of outlet ring headers 161 and discharged through the fluid outlet 181 of the container 121. In one embodiment, the container fluid outlet 181 may be fluidically coupled and connected to one of the outlet ring headers 161. Similarly, the header inlet pipe 162 may be fluidically coupled and connected to one of the inlet ring headers 160. The inlet pipes 162 and outlet pipes 163 can be formed from suitable metal piping with an appropriate configuration.

[0097] The heat exchanger tube 141 may crack and leak over time because, each time the heat (thermal energy) stored in the PCM is transferred to and absorbed by the water flowing through the PCM bed B within the heat exchanger tube 141, the granular PCM undergoes a periodic phase change between a liquid / molten state and at least partially solid. The corrosive properties of the PCM, such as certain molten salts, can corrode the tube material, potentially causing cracking and leaks over time. In either of these situations, replacement of the tube and shutdown of the affected thermal energy storage vessel 121 will be necessary.

[0098] Advantageously, the tube cartridges 142 disclosed herein allow for the rapid replacement of individual cartridges and their associated tubes (some of which may leak) with identical new, fully pre-assembled tube cartridges without removing the closing lid 125 of the thermal energy storage vessel 121. This eliminates the time-consuming task of replacing or filling individual leaking heat exchanger tubes. Damaged and leaking tubes in the old tube cartridges may be replaced / repaired after the thermal energy storage vessel 121 has been made operational. This dramatically simplifies vessel maintenance and repair, reduces downtime, and consequently allows the vessel to return to operation more quickly, minimizing revenue loss.

[0099] Each thermal energy containment vessel 121 provided includes an array of heaters embedded in a molten phase-change material (PCM) and capable of operating to heat the PCM. The heaters are configured to be electrically coupled to an available power source, such as via commercially available electrical contacts or connectors, for the intended application. The power source may be a commercial regional power grid managed by a public utility, or, in some cases, a local power source such as power generation at an industrial plant. The heaters convert the electricity received from the power source into thermal energy used to heat the PCM.

[0100] Figure 3-14 shows various PCM heaters. In one embodiment, the heater 170 comprises a plurality of longitudinally elongated bayonet-type heating elements 170, each having an inner ceramic core 172 and an outer metal sheath 171 that is in direct contact with the PCM in the internal cavity 122 of the thermal energy storage container 121. The heating elements are longitudinally elongated / oriented and may have a cylindrical configuration. The heating elements 170 are scattered radially between the longitudinal tube cartridge 142 and the associated heat exchanger tubes 141, as shown in the figure. A suitable number of heating elements may be provided as needed to sufficiently heat and melt the PCM.

[0101] The upper ends 174 of the heating elements 170 are each positioned within and pass through openings 175 configured complementary to the upper closing lid 125 of the thermal energy storage container 121 (see, for example, Figures 5 and 14). The upper parts 174 define radially projecting annular mounting flanges 176, which seat on the exposed upper surface of the upper closing lid 125 of the container. The upper cylindrical electrical connection boss 173 of each heating element 170 protrudes upward from the lid and includes electrical contacts / terminals for electrical connection to the power source or power supply of the container 121.

[0102] The heating element 170, like the individual heat exchanger tube cartridges 142 described earlier in this specification, is suspended and cantilevered and detachably attached to the upper closing lid 125 of the thermal energy storage vessel 121. Therefore, there is nothing to support the heating element within the internal cavity 122 of the vessel except below the upper lid. Advantageously, the heating element 170 can be replaced without removing the upper closing lid 125 to access the internal cavity of the vessel 121, which makes the replacement of the heating element more convenient and reduces replacement costs.

[0103] In some embodiments, the heating element 170 has a longitudinal length or height that extends over most of the internal cavity 122 of the container 121 containing the PCM, and substantially over the entire height (see, for example, Figure 13). In some embodiments, the heating element 170 has a longitudinal height or length that is longer than the heat exchanger tube cartridge 142. This ensures that the entire capture bed of granular PCM in the container cavity 122 (if in solid form) is exposed to heat from the heating element and melted when energy is supplied to the heating element.

[0104] Once the tube cartridge 142 and heating element 170 are installed in the thermal energy storage container 121, the granular PCM fills the gap between the tube 141, the descending tube 152, and the heating element before energy is supplied to the heating element. When energy is supplied to the heating element, the granular PCM particles are converted to a liquid or molten state, occupying the same internal space within the cavity 122 of the container and coming into direct contact with the components to maximize heat transfer to the working fluid in the tube.

[0105] To initially fill the thermal energy containment vessel 121 with PCM, a filling and pressure release combination device 166 is provided, configured to penetrate the upper closing lid 125 of the vessel (see, for example, Figure 5). The device 166 is in fluid communication with the internal vessel cavity 122 via a PCM transfer pipe 167 of appropriate configuration. This device is openable and closable to fill the PCM and can be closed after PCM filling is complete. If the pressure inside the thermal energy containment vessel 121 exceeds a preset maximum set pressure of the device, the device opens to release the excess pressure to the atmosphere. Suitable commercially available or custom-made devices may be used to provide the required functionality.

[0106] According to another aspect of the present invention, the thermal energy storage system is advantageously modular by nature. In other words, a plurality of thermal energy storage vessels 121 may be provided for any installation to meet the design and operating requirements of a facility that utilizes them to heat a working fluid via the thermal energy stored in the PCM (phase change material) beds within each vessel. Applications of this system include the generation of hot water (or mixed water such as glycol and water) for district heating, industrial processes, and other heated liquid applications, and the generation of steam for steam heating, industrial processes, power generation, and other applications. The number of thermal energy storage vessels 121 to be arranged is selected to generate a working fluid in a liquid or gaseous (e.g., steam) state in sufficient volume / amount and temperature to meet the needs of the intended application. In addition, but not limited to, additional working fluid heating capacity can be added to the existing modular system in response to increasing demand, such as an increase in population and infrastructure (e.g., housing) in district heating or other applications.

[0107] To meet the capacity and temperature requirements of the heated working fluid, individual thermal energy containers 121 can be fluidically coupled in a series flow configuration (see, for example, Figure 2) or a parallel flow configuration. Thus, any suitable flow scheme can be used. Selecting the number of thermal energy containers 121, the thermal service load, and the fluid configuration as needed is within the scope of those skilled in the art.

[0108] A suitable PCM (phase change material) can be used, customized and selected to match the required heat load and operating parameters (i.e., heating the working fluid, which is a mixture of water and water, from the inlet temperature into the thermal energy storage container 121 to the desired outlet temperature). In a preferred but non-limiting embodiment, the PCM is a salt, which may be converted from a granular solid state to a molten state when heated by the heating element 170 when energized by electricity extracted from an available power source such as a power grid or other source. A suitable salt can be used, selected according to the required heat load.

[0109] Some examples of salts that can be used to form the PCM bed B in each thermal energy storage container 121 are shown in the table below: [Table 1]

[0110] The melting temperature and latent heat properties of a salt are characteristics and factors that indicate the selection of a salt suitable for the required heat load and working fluid temperature rise. Therefore, it should be noted that the type of salt used in each heat energy storage container 121 of the green boiler 120 in the applications of the green heat energy storage and power generation system 100 shown in Figure 1B (i.e., preheater, boiler, and superheater) may be customized and different. It will be apparent to those skilled in the art that, regardless of the application, such as simply heating water for district heating, the heat load and performance of the heat energy storage container 121 can be highly customized to meet the required temperature rise targets of the heat energy system.

[0111] The thermal energy storage vessel 121 disclosed herein is described, but not limited to, heating water for various purposes and applications (e.g., boiler feedwater, water-glycol mixtures, or ordinary water) via a thermal energy absorbing PCM bed; however, the present invention is not limited in this respect. Thus, the thermal energy storage vessel 121 can be used to heat any kind of fluid that can flow through the heat exchanger tubes of the vessel. Therefore, countless applications of the green thermal energy storage system 100 are possible and within the scope of this disclosure.

[0112] While the foregoing description and drawings represent exemplary embodiments of the present disclosure, it will be understood that various additions, modifications, and substitutions can be made without departing from the spirit and scope of the appended claims and the scope of equivalents. In particular, it will be apparent to those skilled in the art that the present invention can be embodied in other forms, structures, arrangements, proportions, dimensions, and other elements, materials, and components without departing from its spirit or essential features. Furthermore, numerous modifications of the methods / processes described herein can be made within the scope of this disclosure. Those skilled in the art will also understand that these embodiments can be used with many modifications, such as changes to the structure, arrangement, proportions, dimensions, materials, and components used in the implementation of this disclosure, to be particularly suited to specific environmental and operating requirements, without departing from the principles described herein. Therefore, the embodiments disclosed herein are considered illustrative and not restrictive in all respects. The appended claims should be interpreted broadly to include other modifications and embodiments of this disclosure that can be made by those skilled in the art without departing from their scope and the scope of equivalents.

Claims

1. A body defining a cavity containing a phase-change material capable of storing thermal energy; A top closing lid with multiple openings; A heat source embedded in the phase change material, the heat source being operably connected to a green energy power plant to transfer thermal energy to the phase change material; A plurality of heat exchangers embedded in the phase change material, each of the plurality of heat exchangers being aligned with a corresponding one of the plurality of openings of the upper closing lid, each of the plurality of heat exchangers comprising a tube bundle passing through the corresponding one of the plurality of openings of the upper closing lid, and each of the plurality of heat exchangers being configured to transport a working fluid through the tube bundle in order to absorb thermal energy from the phase change material; Thermal energy containment vessel.

2. The working fluid includes water; A thermal energy storage vessel according to claim 1.

3. The thermal energy storage container is configured to change the water entering the thermal energy storage container from a liquid state to vapor that exits the thermal energy storage container; The thermal energy storage vessel according to claim 2.

4. The thermal energy storage container is configured to receive the water in a liquid state at a first temperature and to discharge the water in a liquid state at a second temperature higher than the first temperature; The thermal energy storage vessel according to claim 2.

5. The thermal energy storage vessel is configured to receive saturated steam at a first steam temperature and discharge the superheated steam at a second temperature higher than the first steam temperature; The thermal energy storage vessel according to claim 2.

6. The body of the thermal energy storage container comprises a side wall having an innermost shell and an outermost shell, and a vacuum annular body formed between the innermost shell and the outermost shell, which is exhausted to below atmospheric pressure; A thermal energy storage vessel according to claim 1.

7. The thermal energy storage container further comprises an insulating annular body formed between the innermost shell and the outermost shell, which includes an insulating material configured to retain heat within the cavity of the thermal energy storage container; The thermal energy storage container according to claim 6.

8. The vacuum annular body is formed between the outermost shell and an intermediate shell adjacent to the outermost shell, and the insulating annular body is formed between the intermediate shell and the innermost shell; The thermal energy storage vessel according to claim 7.

9. The innermost shell, the outermost shell, and the intermediate shell are formed of stainless steel; The thermal energy storage container according to claim 8.

10. The opposing surfaces of the outermost shell and the intermediate shell, facing the inside of the vacuum annular body, are polished to form reflective surfaces that reflect heat; The thermal energy storage vessel according to claim 9.

11. The phase change material is operable to change from a granular solid state to a liquid state when heated by thermal energy released from the heat source; A thermal energy storage vessel according to claim 1.

12. The phase change material is a salt; A thermal energy storage vessel according to any one of claims 1 to 11.

13. A closed flow loop comprising a steam turbine, a steam condenser, a boiler assembly, and a pump for circulating boiler feedwater through the closed flow loop, all of which are in fluid communication with each other; A green energy power plant operably connected to the aforementioned boiler assembly; The system comprises a steam turbine and a generator operably connected to the power grid; The boiler assembly includes a thermal energy boiler vessel and a thermal energy superheater vessel fluidly coupled to the thermal energy boiler vessel, and the thermal energy boiler vessel and the thermal energy superheater vessel are A body defining a cavity containing a phase-change material capable of storing thermal energy; A top closing lid with multiple openings; A heat source embedded in the phase change material, the heat source being operably coupled to the green energy power plant and transferring thermal energy to the phase change material; A plurality of heat exchangers embedded in the phase change material, each of the plurality of heat exchangers being aligned with a corresponding one of the plurality of openings of the upper closing lid, each of the plurality of heat exchangers comprising a tube bundle passing through the corresponding one of the plurality of openings of the upper closing lid, and each of the plurality of heat exchangers being configured to transport boiler feedwater through the tube bundle; The thermal energy boiler vessel is configured to receive boiler feedwater in a liquid state, which is heated by the phase change material inside to produce saturated steam; and the thermal energy superheater vessel is configured to receive saturated steam, which is heated to a superheated state by the phase change material inside to become superheated steam; The superheated steam passes through the steam turbine, rotating the generator to produce electricity; Thermal energy storage and power generation systems.

14. The body of the thermal energy boiler vessel is cylindrical and comprises a longitudinally elongated side wall having an innermost shell and an outermost shell, a vacuum annular body formed between the innermost shell and the outermost shell and exhausted to below atmospheric pressure, and an insulating material configured to retain heat within the cavity of the thermal energy boiler vessel, comprising an insulating annular body formed between the innermost shell and the outermost shell; The thermal energy storage and power generation system according to claim 13.

15. A thermal energy storage container comprising a cavity containing a solid phase-change material, an upper closing lid having a plurality of openings, and a plurality of heat exchangers embedded in the phase-change material, each of the plurality of heat exchangers being aligned with a corresponding one of the plurality of openings in the upper closing lid, and each of the plurality of heat exchangers having a tube bundle passing through the corresponding one of the plurality of openings in the upper closing lid, is provided; A heat source heating step, which involves heating a heat source embedded in the phase change material to heat the phase change material and change it from a solid state to a molten state; The process includes a flow step of flowing a working fluid at a first temperature through the phase change material and heating the working fluid to a higher second temperature; A method for heating a working fluid.

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