Green Energy Thermal Storage System

Abstract

The green boiler includes a thermal energy storage vessel including a captive bed of a thermal mass composition operable to store thermal energy, an array of heaters embedded in the mass, and at least one heat exchanger comprising a tube bundle. The heaters in one embodiment are electric and can be connected to a power source to heat the thermal mass. The tube bundle comprises tubes embedded in the thermal mass composition and is configured to convey a heat transfer fluid (e.g., water) through the tube side of the tubes. During operation, the heat transfer fluid is heated by absorbing stored thermal energy from the thermal mass composition. The thermal mass composition, in some embodiments, can be heated by electricity drawn from the grid during off-peak demand periods. The vessel can produce heated water or steam for district heating, or steam for power generation or industrial uses.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 386,200, filed December 6, 2022, and U.S. Provisional Patent Application No. 63 / 407,872, filed September 19, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to energy storage systems, and more particularly to systems that utilize heat-absorbing thermal mass compositions operable to store heat or thermal energy from electricity extracted from an electric grid or other power source, to generate hot water for district heating or other purposes, or steam for industrial purposes, or to generate electricity via a Rankine cycle during peak load demands on the electric grid. [Background technology]

[0003] As the transition from traditional energy generation to non-polluting "green" energy accelerates, tens of thousands of fossil-fuel power plants (especially coal-fired plants) around the world are heading for early closure or retirement. In fact, fueled by a new consensus to decarbonize the economy, the process of retiring older fossil-fuel power plants has already begun in favor of more environmentally friendly, non-polluting "green" power generation alternatives. The traditional steam-to-electricity Rankine power cycle, shown in Figure 1A, requires green energy alternatives to replace fossil-fuel boilers.

[0004] Green energy alternatives are also needed to replace the fossil fuel boilers used to produce hot water for district heating, which are used in some municipalities and cities.

[0005] One consequence of the increase in renewable green energy is increased fluctuations in power generation levels (highs and lows), which necessitates energy storage systems to smooth out the power supplied to the power grid by these green power generation systems. Summary of the Invention

[0006] The present disclosure provides an environmentally friendly, "green" thermal energy storage system that utilizes stored thermal energy to heat a working heat transfer fluid (e.g., working fluid) as needed to produce a heated liquid and / or vapor. In some embodiments and applications, the heat transfer fluid may be water, although other types of working heat transfer fluids may be used in certain other applications.

[0007] The green thermal energy storage system of the present invention generally comprises a "green" boiler including a thermal energy storage (TES) vessel that is insulated and one or more heat exchangers integrated into the vessel supported by a single housing and forming an integral part of the vessel. The heat exchangers each comprise tube bundles embedded directly in the thermal mass composition within the TES vessel and, in some embodiments, may be steam generators operatively configured to heat a heat transfer fluid (e.g., water) in a liquid state and convert it to steam. In other embodiments, the heat exchangers are operatively configured to heat the heat transfer fluid to an operating temperature, and the heat transfer fluid may remain in a liquid state both before and after being heated within the vessel.

[0008] The interior of the TES vessel contains a "captive" bed of thermal mass composition formulated and operable to absorb and store heat obtained from at least one heater embedded within the vessel, which heats the thermal mass composition. The heater may be an electric heater connected to a power source, and in certain embodiments, multiple heaters may be provided to heat the thermal mass. In other possible embodiments, the heater may include a secondary heat exchanger that conveys a second heat transfer fluid through the bed of thermal mass composition on the inner tube side of the tube bundle for the purpose of heating the thermal mass. This differs from the heat exchangers described above that circulate a working heat transfer fluid through the thermal mass bed to perform work (e.g., electricity generation, district heating, etc.). The term "captive" used above means that the thermal mass composition remains stationary and does not enter or exit the vessel. Thus, the heat exchanger circulates the working heat transfer fluid within the tubes (tube side) of the tube bundle through the thermal mass composition, releasing the thermal energy stored by the thermal mass composition for absorption by the heated heat transfer fluid. In contrast, in one embodiment, the bed of captive thermal mass composition contained in the TES vessel remains stationary and does not flow in or out of the vessel.

[0009] In one non-limiting embodiment, the thermal mass composition can include a mixture having a phase change material (PCM) in combination with one or more other metallic materials described further herein, all of which have heat absorption properties that allow them to absorb and retain heat over a period of time. Both the PCM and the mixture material may be in the form of solid granular particles at room temperature when not heated by the thermal mass composition. In one embodiment, the PCM material preferably has a lower melting point than the metallic material so that the metallic material melts when heated in its solid particle state by an electric heater. The thermal mass composition heats a heat transfer fluid flowing through one or more heat exchanger tube bundles as needed to generate steam for power generation or industry, or hot water for district heating or industry.

[0010] In any end use of the thermal energy storage system of the present invention, it is preferred to extract power from a power source, such as an electrical grid, to heat the thermal mass composition within the container during off-peak load demand periods when energy prices are low. However, the thermal energy storage system may also extract power from the electrical grid during other periods, including peak load demand periods, as needed. Thus, the timing of drawing power from the electrical grid or other source for storage as thermal energy is not limited to any particular time period, but is a matter of economics and heating or electricity demand.

[0011] The combined green thermal energy storage and Rankine power generation system of the present disclosure provides a means for adapting the power output of a power generation system to meet the fluctuating load demands of the power grid. The system can be retrofitted to existing fossil energy power generation facilities or used in new power generation facilities in conjunction with conventional Rankine steam power generation operations well known in the industry. The turbine generator (i.e., steam turbine and generator set) and associated remaining balance of plant Rankine cycle equipment infrastructure remain the same as shown in FIG. 1B.

[0012] The green thermal energy system of the present invention may obtain input energy from the power grid, or alternatively may obtain at least part of it from a dedicated associated solar power plant, wind power plant, or nuclear power plant that is co-located with the green thermal energy storage vessel.

[0013] The concept of the present green thermal energy storage system relies on the fact that the electricity supplied to the power grid from power plants exceeds the electricity demand of actual consumers (industrial, commercial, or residential) for most of the 24-hour period of the day. This means that there are times when cheap excess electricity is available but unfortunately goes to waste. The present system takes excess energy directly from the power grid, or alternatively from a co-located green energy plant (such as solar, wind, or nuclear), and thermally stores the energy in a bed of thermal mass composition stored in a TES vessel.

[0014] In some embodiments, intermittent renewable energy sources, such as solar or wind power, can be used instead of or in addition to charging the thermal mass of a green boiler with thermal energy. For example, a solar energy source can heat the composition by circulating a working fluid, such as molten salt or thermal oil, through a solar collector and then through heat exchange tubes embedded in the thermal mass of the green boiler to heat the composition. The solar collector can be a concentrated solar power (CSP) system that includes a centrally located power tower and an array of reflectors (heliostats) that concentrate sunlight onto one or more thermal receivers, which heat the working fluid. Such systems are well known to those skilled in the art and need not be described in further detail. The heated working fluid flows through heat exchange tubes embedded in the thermal mass of the green boiler to heat the bed. Alternatively, or in addition, multiple wind turbines can be used with onboard generators that generate electricity to power electric immersion heaters embedded in the mass. Such solar collector and wind turbine systems are well known in the art and require no further description. It should be noted that the thermal energy storage system can be configured to switch between thermally charging the bed of thermal mass composition with off-peak energy extracted from the power grid when available (such as at night) and intermittent energy from sunlight (during the day) or wind (day and night) when available. This allows for significant operational flexibility to thermally charge the green boiler using the cheapest power source during a particular period, resulting in considerable economic benefits.

[0015] To generate electricity, a green boiler, including one or more steam generators, is configured and operated to boil boiler feedwater (feedwater) to generate high-pressure superheated steam in a Rankine cycle to generate electricity "on demand" whenever the grid faces a power shortage. This allows the green thermal energy storage vessel to function as a peaking power generating unit, replacing traditional small natural gas or diesel peaking power generating units used during periods of power grid load fluctuations. In other words, the green thermal energy storage vessel is activated when power demand exceeds the supply available from the grid's baseload units. This converts traditional large, polluting fossil-fuel power plants with fossil-fuel boilers into on-demand clean energy generators that can serve as peaking power generators.

[0016] In district heating applications, a green boiler equipped with one or more heat exchangers uses the thermal energy stored in the thermal mass composition bed to heat water, in one embodiment, to produce hot water that can be pumped and distributed to local towns and cities for heating buildings. The water is heated to approximately 200 degrees Fahrenheit (93 degrees Celsius) and remains in a saturated, but not boiling, liquid state for heating purposes.

[0017] In other embodiments for district heating applications, a green boiler including one or more steam generators may be configured to produce low-pressure steam (e.g., less than 150 psig [1.034 kPa]) from water. Such low-pressure steam may alternatively be used for industrial purposes or other applications requiring low-pressure steam.

[0018] Multiple TES vessels can be arranged in a parallel-flow arrangement and fluidly coupled to provide a total volume of high-pressure superheated steam, low-pressure steam, or hot water (or other heat transfer fluid) for the purposes described above. Advantageously, this provides a modular system that allows additional TES vessels to be added over time as needed to accommodate increased power generation capacity at a power generation site, increased industrial needs for low-pressure steam or hot water, or increased district heating demands due to population and infrastructure expansion. The present thermal energy storage system thus provides great flexibility to accommodate service and infrastructure expansion. [Brief explanation of the drawings]

[0019] Features of exemplary embodiments of the present invention will be described with reference to the following drawings: In the drawings, like elements are labeled with like symbols.

[0020] [Figure 1A] 1 is a schematic diagram of a conventional Rankine power cycle system that uses a polluting emitting fossil fuel boiler to generate steam.

[0021] [Figure 1B] 1 is a schematic diagram of a Rankine power cycle system including a green boiler including a thermal energy storage (TES) vessel according to the present disclosure for generating high pressure steam for the Rankine power cycle;

[0022] [Figure 1C] 1 is a schematic diagram of a district heating system including a green boiler including a TES vessel according to the present disclosure for generating low pressure steam or hot water for district heating.

[0023] [Figure 2] FIG. 1 is a top perspective view of the Green Boiler TES vessel showing the optional penthouse (only the structural frame is shown).

[0024] [Figure 3] This is a side view of the TES container.

[0025] [Figure 4] FIG. 1 is a top perspective view of the TES vessel with the optional penthouse removed, revealing the vessel's heat exchanger top header.

[0026] [Figure 5] FIG. 5 is an enlarged view of the upper part of the TES container in FIG. 4.

[0027] [Figure 6] FIG. 1 is a bottom perspective view of a TES container.

[0028] [Figure 7] FIG. 1 is a first side view of the TES container.

[0029] [Figure 8] This is a second side view of the TES container.

[0030] [Figure 9] This is a third side view of the TES container.

[0031] [Figure 10] This is a fourth side view (of the TES container).

[0032] [Figure 11] This is a top view of the TES container.

[0033] [Figure 12] This is a bottom view of the TES container.

[0034] [Figure 13] FIG. 1 is a first cross-sectional side view of the TES container.

[0035] [Figure 14] FIG. 14 is an enlarged view of the top portion of the TES vessel cut out from FIG. 13.

[0036] [Figure 15] FIG. 14 is an enlarged view of the bottom portion of the TES container cut out from FIG. 13.

[0037] [Figure 16] FIG. 10 is a second cross-sectional side view of the TES container.

[0038] [Figure 17] FIG. 17 is an enlarged view of the top portion of the TES vessel cut out from FIG. 16.

[0039] [Figure 18] FIG. 17 is an enlarged view of the bottom portion of the TES container cut out from FIG. 16.

[0040] [Figure 19] FIG. 1 is a top perspective view of the TES vessel with one sidewall removed, showing the vessel's interior cavity and the electric heater bank and heat exchanger tubes of the vessel's heat exchanger.

[0041] [Figure 20] FIG. 20 is a close-up view of the bottom portion of the TES vessel cut from FIG. 19, showing one of the slide-insertable heaters deployed outward.

[0042] [Figure 21] FIG. 1 is an enlarged perspective view of the bottom portion of the TES vessel without the sidewalls and heaters, showing the tube bundles and tube support structure or frame of the heat exchanger within the TES vessel.

[0043] [Figure 22] FIG. 1 is a schematic diagram of a portion of a TES vessel showing one of the heat exchangers and the tube-side flow path (indicated by flow arrows) of a heat transfer fluid circulating through the tubes of the heat exchanger embedded in a thermal mass composition that operates to retain and release heat.

[0044] [Figure 23] FIG. 1 is a top perspective view of the TES vessel showing the outer insulation installed on the vessel.

[0045] [Figure 24] FIG. 1 is a side view of a pair of heat exchangers of a TES vessel, showing the tube bundles of the heat exchangers separated and showing the tube grid supports.

[0046] [Figure 25] FIG. 10 is a top view of the tube grid support.

[0047] [Figure 26] FIG. 10 is an enlarged detail view of the upper tubesheet of one of the heat exchangers, showing the upper portion of a single heat exchanger tube and a corresponding discharge extension tube located in the upper header.

[0048] [Figure 27] 10 is an additional side view of the TES vessel, showing a portion of the side wall of the side plate removed to reveal the vessel's internal cavity.

[0049] [Figure 28] FIG. 1 is an enlarged side cross-sectional view of the upper header of one of the heat exchangers, showing the upper sheet and steam demister mounted within the upper flow plenum formed by the header.

[0050] [Figure 29] FIG. 1 is a schematic diagram showing the inlet and outlet piping network of a TES vessel associated with heat transfer fluid entering and exiting the vessel's heat exchangers.

[0051] [Figure 30] FIG. 10 is a bottom cross-sectional view of a TES vessel showing an alternative embodiment of a means for heating the thermal mass composition of the vessel, comprising an immersed heat exchanger unit including a heat exchanger tube bundle that conveys heated working fluid through the composition.

[0052] All drawings are schematic and not necessarily to scale. A part numbered in one figure is to be considered the same part appearing in other figures without a numbering designation for the sake of brevity, unless specifically labeled with a different part number and explained herein. Integers referenced herein may include multiple symbols with the same integer but differing alphabetical suffixes, but unless otherwise noted, are to be construed as a general term for all symbols sharing the same integer. DETAILED DESCRIPTION OF THE INVENTION

[0053] The features and advantages of the present invention are shown and described herein with reference to exemplary (example) embodiments. This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire description. It should be apparent, therefore, that the disclosure should not be limited to exemplary embodiments that illustrate some possible non-limiting combinations of features, which may exist alone or in combination with other features.

[0054] In describing the embodiments disclosed herein, references to direction or orientation are for convenience of description only and are not intended to limit the scope of the present invention. Relative terms such as "lower," "upper," "horizontal," "vertical," "upper," "below," "top," "bottom," and derivatives thereof (e.g., "horizontally," "downward," "upward," etc.) should be interpreted as referring to the orientation currently being described or shown in the drawings being discussed. These relative terms are for convenience of description only and do not require that the devices be constructed or operated in a particular orientation. Terms such as "mounted," "fixed," "connected," "coupled," "interconnected," and the like refer to a relationship in which structures are movably or fixedly fixed or attached to one another, either directly or indirectly through intervening structures, unless expressly stated otherwise.

[0055] Throughout this specification, ranges disclosed herein are used in shorthand to describe all values ​​within the range. Any value within the range can be selected as the endpoint of the range. Furthermore, all prior patent or patent application documents cited herein are incorporated by reference in their entirety. In the event of a conflict between the definitions of this disclosure and those of the cited documents, this disclosure shall control.

[0056] FIG. 1A illustrates a conventional steam-to-electricity Rankine power cycle with a large fossil-fuel boiler to generate the steam needed to generate electricity. The basic cycle equipment (excluding auxiliary systems) includes a fossil-fuel-fired boiler (coal, oil, natural gas, etc.), a steam turbine-generator set, a steam condenser that condenses the steam exhausted from the steam turbine back into a liquid, and a boiler feedwater pump that circulates boiler feedwater (heat transfer fluid) taken from the condenser through a closed flow loop formed by piping fluidly connecting the components as shown. An electric generator is mechanically coupled to the steam turbine and electrically coupled to an electric power grid (represented by the illustrated transmission tower). Steam generated by the boiler rotates a turbine shaft via a row of turbine blades, which in turn rotates the generator rotor within a stator (magnets), converting mechanical energy to electrical energy in a known manner. Rankine cycle power generation systems and their power generation operation are well known to those skilled in the art and need not be described in further detail.

[0057] Fossil-fuel boilers in Rankine systems, which convert liquid boiler feedwater into high-pressure steam, have traditionally been used for base electrical load operation to meet the base load demands of the power grid because such boilers and associated auxiliary equipment cannot be quickly started for on-demand power generation. In fact, the entire start-up process of a fossil-fuel base-load plant takes a significant amount of time to bring all equipment and systems up to full pressure and temperature operating conditions and reach full load.

[0058] 1B illustrates a clean energy "green" Rankine power cycle system including a green boiler 120 according to the present disclosure. The green boiler, a partial thermal energy storage device, replaces the fossil fuel steam boiler of FIG. 1A with a thermal energy containment vessel 130 configured as both a containment for a heat-retaining thermal mass composition and one or more heat exchangers, as further described herein.

[0059] The thermal energy storage system 100 of the present invention used for power generation in Figure 1B includes a green boiler 120 and can be configured and used as a "peaking" power generation system to generate and supply electricity to the power grid during periods of peak load demand. The green boiler can be rapidly initiated "on demand" to generate the steam necessary to run the Rankine cycle. Preferably, the electrical energy used to "load" and heat the thermal mass composition is drawn from the power grid, whenever possible, during "off-peak" load demand periods when there is a surplus of energy on the power grid.

[0060] The green thermal energy storage system 100 shown in FIG. 1B may include a conventional steam turbine / generator set including, but not limited to, a steam turbine 102, a generator 103 mechanically coupled thereto and operatively connected to a power grid 104, a steam condenser 105, a boiler feedwater pump 106, and a green boiler 120 including a thermal mass composition operable to absorb and release heat on demand. The generator generates electricity in a conventional manner via a stator and rotor assembly, as known in the art. The feedwater pump circulates boiler feedwater through a closed flow loop 110 formed by piping or other flow paths fluidly coupling the water-carrying components of the Rankine cycle, as shown. With the exception of the green boiler assembly, the remaining plant components of the clean energy Rankine cycle operate to generate electricity in the same previously known manner as a conventional Rankine cycle.

[0061] 1C illustrates the application of a green boiler 120 according to the present disclosure for a thermal energy storage district heating system 101, including commercial, industrial, and residential heating applications. Hot water or low-pressure steam produced by the green boiler is pumped via one or more pumps 106 through a closed flow loop 110 to multiple end-use points requiring heating (e.g., radiators, etc.). The district heating flow distribution network 111 is collectively represented by a box in FIG. 1C and can include residential and commercial heating end-uses. After rejecting heat for heating, the cooled water (or condensate in a low-pressure steam district heating system) is collected and returned via the flow loop 110 to the green boiler, where it is reheated and continues to repeat the same heating and distribution cycle.

[0062] 2-28 show various views of a thermal energy storage system according to the present disclosure that can be used for power generation, district heating, or other applications. The system has wide applicability and is not limited to applications for various purposes such as providing hot water or low-pressure / high-pressure steam. Steam pressures ranging from about 50 psi (0.345 MPa) to about 3000 psi (20.68 MPa) can be generated to meet a variety of steam needs and applications.

[0063] The thermal energy storage system includes a green boiler 120 including a highly insulated thermal energy storage (TES) vessel 10 combined with one or more heat exchangers 200 operable to heat a heat transfer fluid. In the illustrated non-limiting embodiment, each heat exchanger may be a steam generator 200-1 operable to heat water to produce steam, for example, for power generation, district heating, or industrial applications. In other embodiments, each heat exchanger may be operable to simply increase the temperature of water or other heat transfer fluid that remains in a liquid state before and after heating. For district heating applications, the design of the TES vessel and heat exchangers is similar to the steam generator 200-1 and includes the same features as those shown, although a demister (described further herein) for drying the exiting steam stream is obviously not required and may be omitted. Other features of the TES vessel and heat exchangers may be the same as those described below. Therefore, the steam generator will be described in a broader context using the more general term "heat exchanger 200," which can be used to generate steam or simply increase the temperature of a heat transfer fluid that remains in a liquid state after heating.

[0064] The heat exchanger 200 is integrated directly into the vessel housing 134, forming a single green boiler unit (described in more detail herein). Advantageously, this provides a modular boiler unit that has a small footprint at the installation site and is easy to ship / transport as a single unit that can be factory-fabricated with all bonded (e.g., welded, flanged / bolted, threaded, etc.) internal piping and tubing connections. This improves reliability and reduces installation time at the installation site. Thus, the single-unit construction of the green boiler 120 differs from physically separate individual thermal storage vessels and heat exchangers that must be assembled and piped on-site.

[0065] The TES vessel 130 can be a vertically elongated structure with a generally box-shaped body and structure. For example, the TES vessel 130 can be a rectangular parallelepiped configuration, as shown in the illustrated non-limiting embodiment. Other vessel shapes are also possible, including, but not limited to, hexagonal, cylindrical, and others. The shape of the vessel is not a limitation of the concepts or inventions disclosed herein.

[0066] The TES vessel 130 defines a vertical centerline axis CA that passes through the geometric center of the vessel and provides a reference point to facilitate description and relative orientation of the other components of the vessel.

[0067] The TES vessel generally includes an outer housing 134 defining a top 131, a bottom 132, and a plurality of vertical side walls 133 extending between the top and bottom along an axis CA. The side walls are flat and, in one embodiment, are formed by a plurality of suitable metal side plates 133-1 (e.g., steel or aluminum) attached to an internal structural steel frame framework (not shown to clearly show the working internal components of the vessel). Four side walls 133 are provided, each perpendicular to the adjacent side wall where they meet at a 90-degree angle 133-2. The framework may include suitable vertical, horizontal, and angled structural steel members and braces as needed to support the vessel and its appendages.

[0068] The TES vessel 130 further comprises a support base 138 disposed on the bottom 132 of the vessel housing 134. The mounting base 138 may be a generally horizontal, wide, linear structure configured to be placed on and secured to a flat support structure, such as a concrete foundation slab F. In one embodiment, the base may be bolted to the slab on all four sides using a plurality of threaded fasteners or anchors (not shown) that may be inserted into holes in a gusseted mounting plate 138-1. The mounting base 138 may be formed from suitably strong horizontal and vertical flat metal plates and structural members, such as steel, of suitable thickness, forming the illustrated mounting base configuration in such a manner as to support the full weight of the TES vessel from the foundation slab.

[0069] The TES vessel 130 further includes a substantially flat, horizontal top closure plate 136 on the vessel's top 131 and a substantially flat, horizontal bottom closure plate 137 on the vessel's bottom 132. The plates 136, 137 are formed of a suitable thick metal, such as steel. The top and bottom closure plates are aligned parallel to one another and perpendicular to the vessel's centerline axis CA. Both plates extend completely beyond both sides of the vessel 130 and outer housing 134, as shown. Thus, the top closure plates 136, 137 may each have a substantially rectilinear (i.e., square or rectangular) shape, as opposed to the cylindrical top headers 201, 203, as further described herein. The bottom closure plate 137 is fixedly coupled to and supported by the vessel's support base 138, as previously described.

[0070] The TES receptacle 130 (e.g., housing 134) defines an open, continuous / adjacent vertical interior space or cavity 135 extending vertically along a centerline axis CA between horizontal upper and lower closure plates 136, 137 and laterally / horizontally between the four side walls 133 (i.e., side plates 133-1) of the TES receptacle housing 134. Thus, in the illustrated embodiment, the cavity 135 extends across at least most, and substantially the entire height, of the receptacle housing 134 (excluding the thickness of the upper and lower closure plates of the housing).

[0071] The interior cavity 135 of the TES vessel 130 is filled with a thermal mass composition M (described further herein) that absorbs and retains heat from heaters embedded in the material. The thermal mass composition is contained confined within the vessel 130, so that the material does not enter or leave the TES vessel 130 during operation of the green boiler 120. Only tube-side heat transfer fluid flows through the vessel, as described further herein.

[0072] The heat exchanger 200 of the TES vessel 130 will now be described in more detail.

[0073] 2-28, one heat exchanger is disposed in each of the four sections of the thermal energy storage vessel, forming four fluid heating zones. The heat exchangers 200 are fluidly separable from one another, as described further herein, so that each heating zone can operate independently of the other heating zones to heat heat transfer fluid. This allows for considerable operational flexibility, as only a few heat exchangers may be needed to provide enough vapor or heated liquid heat transfer fluid to meet end-use demands.

[0074] Each heat exchanger 200 generally comprises a top channel or header 201 including a top tubesheet 202 and a bottom channel or header 203 including a bottom tubesheet 204. The top header 201 is located at the top 131 of the TES vessel 130, and the bottom header 203 is located at the bottom 132 of the vessel. Each tubesheet 202, 204 may be circular in one embodiment.

[0075] Each heat exchanger 200 further comprises a tube bundle 210 including a plurality of elongated heat exchanger tubes 211 extending vertically between a top tube sheet 202 and a bottom tube sheet 204. The tubes 211 may be straight, in one embodiment, as shown. The tube sheet is a relatively thick structure, e.g., approximately 4 inches (10.2 cm) thick in one embodiment. The upper ends of the tubes are secured to and sealably bonded to the top sheet 202 by a circumferential seal weld. It should be noted that the tubes 211 pass through complementary configured holes in the top plate 136 but are not secured to the top plate and are slidable relative to the top plate.

[0076] In a vane similar to that of the upper tubesheet 202, the lower ends of the tubes 211 are fixed to the lower tubesheet 204 in the same manner and hermetically seal welded. The tubes 211 penetrate completely through the top and bottom tubesheets with complementary configured through-holes 211-1 (see, e.g., FIG. 26, which shows the upper tubesheet-to-tube interface). A similar structure with through-holes is used for the lower tube ends and bottom tubesheet 204 (see, e.g., FIG. 15). This places each heat exchanger tube 211 in fluid communication with both the upper header 201 and the bottom header 203, allowing heat transfer fluid to be exchanged between them via the flow of heat transfer fluid (see FIG. 22, which shows the tube-side heat transfer fluid circulation pattern indicated by the flow arrows).

[0077] The top header 201 defines an open interior space that forms the upper flow plenum 201-1 of the heat exchanger. The bottom header 203 similarly defines an open interior space, which defines the lower flow plenum 203-1. A heat transfer fluid (e.g., water or the like) flows through the tubes 211 of the tube bundle 210 on the tube-side of the tubes. The bottom flow plenum 203-1 receives the heat transfer fluid in a cooled, liquid state and distributes the fluid to the lower inlet ends of each tube 211 in the tube bundle 210. Similarly, the top flow plenum 201-1 receives and collects the heat transfer fluid from the upper outlet ends of each tube 211 after it has been heated by the thermal mass composition within the TES vessel 130. Thus, as shown in the flow diagram of FIG. 22, the flow of the heat transfer fluid through the tubes 211 in this embodiment is vertically upward within the vessel from the bottom header 203 to the top header 201.

[0078] The heat exchanger tubes 211 are embedded in thermal mass composition M such that the thermal mass composition fills the gaps or voids between the tubes of the tube bundle 210 and provides direct conformal contact with the outer surfaces of the tubes for optimal heat transfer. Thermal mass composition M is further described herein.

[0079] In one non-limiting embodiment, the top header 201 and the bottom header 203 may comprise generally tubular, hollow, cylindrical metal body structures formed by vertically oriented annular shells 201-3 and 203-3, respectively. The shells define circumferentially extending vertical sides of the headers, as shown. The shell 203-3 of the bottom header 203 extends vertically and is sandwiched and welded between the top bottom tubesheet 204 and the bottom closure plate 137 of the bottom TES vessel housing 134. Thus, the top and bottom ends of the shell 203-3 are seal-welded to the bottom tubesheet and bottom closure plate, respectively, of the housing, forming a leak-tight bottom flow plenum 203-1 within the bottom header 203. This secures the bottom tubesheet 204 in place within the vessel.

[0080] The shell 201-3 of the upper header 201 protrudes upward from the upper closure plate 136 of the TES vessel housing. The domed head 201-2 is seal-welded to the upper end of the shell 201-3, forming a leak-tight upper flow plenum 201-1 within the upper header 201. In some embodiments, the head may be an elliptical or hemispherical head, although other dome-shaped configurations may be used. A fluid outlet 212 in the form of a protruding short section of piping is located on the domed head of each upper header to discharge heated heat transfer fluid (in liquid or vapor form) from the upper header. The flow of heat transfer fluid from the TES vessel 130 is controlled by a fluid outlet valve 212-1 (see, for example, FIG. 22 ). In one embodiment, the fluid outlet 212 may be centrally located at the top of the head to collect the liquid or vapor phase heat transfer fluid exiting the TES vessel 130 after being heated. The fluid outlets from each heat exchanger may be fluidly combined to form a single heated heat transfer fluid stream that exits the vessel and enters the closed flow loop 110 shown in Figures 1B and 1C (see, e.g., Figure 29, described further herein).

[0081] The upper tubesheet 202 employs a floating tubesheet design to accommodate the vertical thermal expansion and contraction of the tubes 211 in the tube bundles 210 of the four heat exchangers 200 as the heat transfer fluid is heated within the TES vessel 130. The circular upper tubesheet 202 is surrounded by an annular metal thermal expansion sleeve 201-4, the bottom of which is welded to the upper closure plate 136 of the TES vessel (see, for example, Figures 5, 17, and 28). Specifically, the lower end of the vertical shell 201-3 of the upper header 201 is fluid-tightly sealed to the top surface of the upper tubesheet 202 by a circumferential seal weld. The weld between the upper header shell 201-3 and the upper sheet 202 is slidably positioned within the expansion sleeve 201-4, as shown in the figures. As the tubes are heated by the thermal mass composition M and thermally grow / expand linearly in length from their initial cold state, the entire tubesheet 202 and upper header 201 structure moves / rises vertically upward relative to the top closure plate 136 of the TES vessel 130, which remains stationary (see the thermal growth / contraction arrows in Figure 17 for directional guidance). Recall that the bottom tubesheet 203 is stationary relative to the TES vessel housing 134. As heat from the thermal mass composition M is transferred to the heat transfer fluid flowing within the tube bundle 210, causing it to cool, the tubes 211 begin to contract. The tubesheet 202 and upper header 201 (including the cylindrical shell 201-3) slide downward within the thermal expansion sleeve 201-4. In a conventional shell-and-tube heat exchanger, both the tube side and the shell side of the vessel are pressurized above atmospheric pressure, while the interior cavity 135 of the TES vessel 130 is at atmospheric pressure. Thus, the heat-expandable sleeve alone is sufficient to provide a relatively tight fit (i.e., minimal annular clearance) and non-pressurized sealing interface to the tubesheet and upper header shell 201-3.

[0082] In accordance with another aspect of the present invention, in applications in which the TES vessel 130 heats water and the water is converted to steam on the tube side of the heat exchange tubes 211 of the tube bundle 210, a demister 213 may be provided. FIG. 28 is an enlarged cross-sectional view of the upper header 201 and demister 213. The demister serves to condition and dry the steam before it is discharged from the upper header 201 through the fluid outlet 212, thereby increasing the "steam quality" (the percentage of saturated steam present in the saturated liquid / vapor (steam) mixture). Higher quality steam is desirable because it typically provides higher heat transfer efficiency.

[0083] In one embodiment, the demister 213 may be formed by an expanded metal mesh panel 213-1 with a plurality of openings between the mesh wires that allow steam to flow through. Collected carryover water droplets entrained in the steam condense on the metal mesh and fall downward from the demister by gravity onto the upper tubesheet 202 in the upper header 201 / flow plenum 201-1 (see, e.g., FIG. 22 ). Collected water (e.g., condensed water) is discharged from the upper header 201 by vertical downcomers 214 fluidly coupled to the upper header 201, such as via drain outlets 215 coupled to the header shell 201-3 as shown. The downcomers, in one non-limiting embodiment, may be formed by pipes and positioned outside the TES vessel housing 134 adjacent the housing sidewall 133. The lower end of each downcomer 214 is fluidly coupled to the bottom header 203 / flow plenum 203-1 via header fluid inlets 217 and returns the discharged water thereto. The fluid inlet may be formed by a short section of piping. Thus, as shown in FIG. 22 , a flow circulation loop is formed by the downcomer 214 between the upper header 201 and the lower header 203 and the tube bundle 110. In the flow circulation loop, a portion of the heated heat transfer fluid exiting the upper ends of the tubes in the upper header 201 circulates through the downcomer 214 to the bottom header 203, as described further herein. The drain outlet 215 of the upper header 201 above the downcomer 214 may also be formed by a short section of piping, but is located at a height close to the top surface of the upper tubesheet 202, for reasons that will become apparent shortly.

[0084] It should be noted that the condensed water collected in the header 201 forms a shallow condensed water pool P having a predetermined surface level 216 (see, for example, FIG. 22). To prevent the steam discharged from the heat exchanger tubes 211 to the upper header 201 from remixing with the accumulated water and rewetting, each tube is provided with a metallic discharge extension tube 220 of sufficient length (e.g., height) and having an open upper end 220-1 positioned above the surface level 216 of the condensed water pool P. FIGS. 26 and 28 show details of the extension tubes. The height of the extension tubes can be set taking into account expected fluctuations in the surface level 216 of the condensed water pool P in the upper header. The lower ends of the extension tubes 220 are welded to the upper surface of the upper tube sheet 202 surrounding each heat exchanger tube 211, and protrude vertically upward by a certain length. A circumferential seal weld is formed on the upper surface of the tubesheet 202 around the upper end of each heat exchanger tube 211 and around each extension tube 220, placing the tubes in direct fluid communication. The drain outlet 215 of the upper header 201 is located at the elevation where accumulated water enters the upper end of the discharge pipe and exits the outlet before mixing with the upwardly flowing steam. Thus, the elevation of the upper end 220-1 of the extension tube 220 is higher than the surface level 216 of the condensate pool P, which is set and fixed by the elevation of the upper header drain outlet 215 as described above.

[0085] In one embodiment, the heat transfer fluid discharged from the top header 201 of each heat exchanger 200 through its respective downcomer 214 to the bottom header 203 heats the heat transfer fluid in the heat exchanger tubes 211 within the TES vessel 130, creating a natural, passive convection thermosiphon circulation flow loop (see, e.g., the heat transfer fluid flow arrows in FIG. 22 ). This creates a natural gravity-driven, heating-driven fluid circulation, not driven by a mechanical pump, through the tube bundles 210 of each heat exchanger 200 on the tube side between the headers 201, 203. The heated fluid becomes less dense and rises, powering the circulation flow. The principles of the thermosiphon effect are well understood by those skilled in the art without further undue explanation.

[0086] The flow of heat transfer fluid through the TES vessel and tube bundles 210 is in a straight, vertically upward path as shown, taking advantage of the natural thermosiphon effect and gravity. The heat transfer fluid rising as it heats up within the tubes 111 of the tube bundles 110 passively draws cold heat transfer fluid returning from the power generation system or district heating system of FIG. 1B or 1C (or other figures) from the return fluid inlet 219 and downcomer 214 coupled to the top header 201 into the bottom header 203 and tube bundles 110, advantageously without the need for or use of a pump.

[0087] Instead of an external downcomer 214, in some embodiments the downcomer may be defined by several heat exchanger tubes 211 within the TES vessel 130 which may be located in a cooler region of the vessel.

[0088] After the hot heat transfer fluid (in liquid or vapor form) exits the TES vessel 130 through the fluid outlet 212 of each heat exchanger 200 to provide heat for power generation, district heating, or other uses, the cooled heat transfer fluid is circulated back to the TES vessel 130 via the closed flow loop 110 previously described herein (see, e.g., FIGS. 1B and 1C). The returning cold or cooled fluid in the closed flow loop 110 can be plumbed directly to each downcomer 214 of the four heat exchangers 200 via a return fluid inlet 219 fluidly connected to each downcomer, as shown, for example, in FIGS. 5 and 22. The flow of heat transfer fluid into the TES vessel 130 is controlled by a fluid inlet valve 219-1 (see, e.g., FIG. 22). The cold heat transfer fluid returning from the closed flow loop 110 mixes with the heated condensed circulation stream flowing down the downcomer from the upper header 201 of each heat exchanger 200 and then enters the bottom header 203 via the fluid inlet 217 connection (see also FIG. 20 ). Because a single stream enters the lower header 204, only one fluid inlet 217 connection is required for each bottom header. Furthermore, because the mixed heat transfer fluid temperature is reached upstream of the bottom header, a uniform temperature of heat transfer fluid enters the bottom header, eliminating fluid temperature variations in various portions of the lower flow plenum 203-1 within these headers. However, alternatively, in other possible embodiments, a separate and independent return fluid inlet 219 may be fluidly connected directly to each separate bottom header 204 of the heat exchanger in addition to the downcomer piping return fluid inlet connection (i.e., the fluid inlet 217 connection) formed in the bottom header 204 of each heat exchanger. Either fluid return arrangement is possible.

[0089] Thermal expansion features 215 may be provided in the downcomer 214 of each heat exchanger 200 to accommodate vertical expansion and contraction of the upper header 201 and floating tubesheet 202 caused by thermal expansion / contraction of the length of the heat exchanger tubes 211 during operation of the TES vessel 130. In one embodiment, the expansion features 215 may include a corrugated, recurved piping loop forming one or two sections of C-shaped piping. The corrugated piping section adds in-line flexibility to the downcomer piping to accommodate vertical thermal movement of the outlet 215 through the shell 201-3 of the upper header 201 to which the piping is coupled, thereby preventing thermal stress-related cracking in the downcomer piping. In other possible embodiments, commercially available piping expansion joints, such as metal bellows-type expansion joints or other types of expansion joints, may be provided in place of the recurved piping loops.

[0090] To support the tube bundles 210 of each heat exchanger 200 within the TES vessel 130, multiple tube grid supports 230 may be positioned within the vessel's interior cavity 135. Referring to Figures 21, 24, and 25, each tube grid support may include an open tube support frame 231 collectively formed by various metal structural frame members 233 (e.g., square or round tubes, rods, C-sections, angles, etc., and combinations thereof) welded into an orthogonal grid, forming open areas 232 therebetween. The open areas allow the granular thermal mass composition M to flow and fill the spaces between the frame members when the TES vessel 130 is not being heated. Advantageously, this forms within the TES vessel 130 a contiguous, continuous bed of material M extending the entire height of the vessel's interior cavity 135.

[0091] A plurality of horizontally spaced tube lateral support collars 235 are welded to each support frame 231 at intervals to define the tube layout of each tube bundle 210. The tubes 211 extend through but are slidably positioned within their respective collars, allowing the tubes to expand and contract vertically upward and downward during operation of the TES vessel 130. The collars 235 thus provide lateral support for the tubes but do not restrict their vertical expansion and contraction. Furthermore, the lateral support collars 235 function to maintain the horizontal spacing of the tubes 211 within the bed of thermal mass composition M within the TES vessel. Each tube bundle 210 of the heat exchanger 200 is supported at multiple elevations from top to bottom of the vessel interior cavity 135 by a plurality of support frames 213 vertically spaced along the height of the tube bundle between the top tube sheet 202 and the bottom tube sheet 204, as shown. The tube support frames 231 may be spaced vertically at any suitable spacing. Each support frame 213 may have a straight, horizontally elongated configuration (e.g., rectangular) as shown in the illustrated non-limiting embodiment. The tube support frames may also be provided in other shapes and configurations.

[0092] Each of the four heat exchangers 200 shown in the illustrated non-limiting embodiment is fluidly isolated from one another on the side of the tubes that carry the heat transfer fluid through the thermal mass composition M within the TES vessel 130. Advantageously, this allows the TES vessel 130 to continue operating even if one heat exchanger is shut down for maintenance / repair (e.g., due to a clogged tube), as the remaining heat exchangers remain fully functional. Furthermore, due to the high degree of operational flexibility, depending on the heat transfer fluid demand (heated liquid or vapor), it may not be necessary to operate all four heat exchangers 200 at all times. Thus, each heat exchanger 200 and its associated exhaust and inlet piping networks are advantageously configured to be fluidly isolated from all other heat exchangers, allowing each heat exchanger to operate independently of the others.

[0093] One non-limiting example of a fluid discharge piping network 248 having a configuration that allows selective isolation of each heat exchanger 200 on the discharge side is shown schematically in Figure 29. While the illustrated embodiment shows a steam generation application, it is equally applicable to the production of a heated liquid heat transfer fluid. Each heat exchanger in the illustrated embodiment is an independently operable "steam generator" in this example.

[0094] Referring to FIG. 29, the fluid discharge piping network 248 includes each heat exchanger having an associated fluid outlet piping 212-2 fluidly coupled at one end to a respective fluid outlet 212 on one of the upper headers 201 and at the other end to a piping manifold 253. The outlet piping 212-2 is shown with a dashed line for convenience in visually distinguishing it from the discharge piping 212-2. As shown, at least one fluid outlet valve 212-1 is installed in and fluidly coupled to the fluid outlet piping 212-2 of each heat exchanger. The heated heat transfer fluid (e.g., steam) discharged from each heat exchanger can be fluidly isolated from the other heat exchangers by selectively closing one or more fluid outlet valves 212-1 associated with each heat exchanger. The manifold 253 collects the heated heat transfer fluid (steam in this example) from each heat exchanger 200 into a single discharge stream that can be routed to the closed flow loop 110 of the system shown in FIG. 1B or 1C (or other figures). The manifold 253 may be formed using any suitable piping diameter and metal material, as desired. In one embodiment, the manifold 253 may be formed of stainless steel for corrosion resistance. Any suitable on-site routing of the fluid outlet piping 212-2 may be used to suitably and conveniently support the piping from the TES vessel 130. It should be noted that discharge piping arrangements and valves other than a manifold may be used to combine the discharges from each heat exchanger and fluidly isolate the discharge sides of the heat exchangers from one another to support independent operation of each heat exchanger.

[0095] One non-limiting example of a fluid inlet piping network 249 having a configuration that allows for selective isolation of each heat exchanger 200 on its inlet side is also shown schematically in Figure 29. The fluid inlet side of the heat exchanger 200 is provided with a multi-branched network of fluid inlet piping 219-2 that splits the single return stream of cold heat transfer fluid from the closed flow loop shown in Figures 1B or 1C (or other steam applications) into multiple streams that flow to the return fluid inlets 219 associated with each heat exchanger 200. By selectively closing one or more return inlet valves 219-1 in each heat exchanger's fluid inlet piping 219-2 (see also Figure 22 above), each heat exchanger on its inlet side can be fluidly isolated from the other heat exchangers. Because the tube bundles 210 of each heat exchanger are already isolated from one another within the internal cavity 135 of the TES vessel 130, as previously described, selectively closing the aforementioned inlet valves 219-1 and outlet valves 212-1 outside the TES vessel 130 allows each heat exchanger 200 to operate completely independently of the other heat exchangers, which, in the illustrated embodiment, advantageously provides considerable flexibility in operation to meet various demands for heated heat transfer fluid, such as steam.

[0096] Continuing with reference to FIG. 29, for steam service, piping manifold 253 can be fluidly coupled downstream to steam reservoir 250 via manifold discharge piping 251-1 under the control of manifold discharge valve 251 (which can be switched to an open or closed position). Discharge from the steam reservoir pressure vessel is fluidly coupled to the downstream intended steam application system via reservoir discharge piping 252-1 under the control of reservoir discharge valve 252. The steam-utilizing system can be the closed flow loop 110 of the system shown in FIG. 1B or 1C in some embodiments described herein above, or in other applications. In some configurations, steam reservoir 250 comprises pressure vessel 250-1, which includes an elongated cylindrical steel outer shell 250-2 defining an open interior volume sized to hold the desired amount of steam generated by heat exchanger 200, to suit the needs of a particular end application. Pressure vessel 250-1 can be oriented horizontally or vertically. A pressure vessel, preferably located near the TES vessel 130, can be used to collect and store the steam generated by the TES vessel until needed. If use is continuous, the steam can pass continuously through the vessel without being temporarily held or stored. Even when used in continuous operation, the steam reservoir 250 provides a buffer to equalize the pressure of the steam received from each heat exchanger 200 before flowing to the downstream end-use application.

[0097] The steam reservoir pressure vessel 250-1 and the aforementioned fluid outlet piping 212-2, reservoir discharge piping 252-1, and manifold discharge piping 251-1 may be heavily insulated to prevent excessive amounts of steam from condensing prior to end use.

[0098] It should be noted that in certain embodiments, manifold 253 may be omitted and fluid outlet piping 212-2 of fluid exhaust piping network 248 may be configured such that the fluid exhaust from each heat exchanger 200 is fluidly coupled directly to steam reservoir 250, independent of the other heat exchangers. In this case, the steam reservoir serves to collect and combine the heated heat transfer fluid (e.g., steam) exhausted from each heat exchanger individually.

[0099] It should also be noted that the same heat exchanger inlet and outlet piping networks 248, 249 shown in Figure 29 and described above, including pipe manifolds 250 configured to fluidly separate each heat exchanger 200 on the piping side from the other heat exchangers, can be used to handle heated heat transfer fluid in a liquid state instead of a vapor. The vapor reservoir pressure vessel may be omitted, or a similar vessel may be used to store heated liquid (e.g., water or other) until needed for the end use.

[0100] Returning now to heat exchanger 200 and referring generally to Figures 1-28 as an applicable example, the tube bundles 210 of each heat exchanger, which define the active heat transfer area of ​​each heat exchanger, may be arranged in a flow pattern that causes a tube-side linear flow through the thermal mass composition, which is a stationary or "confined" mass that does not flow into or out of the TES vessel 130 (see particularly the flow diagram in Figure 22). The heated heat transfer fluid (e.g., liquid or vapor phase) exiting each heat exchanger is fluidly combined and piped together after leaving each heat exchanger's top header 201 to form a single heated fluid stream for district heating, power generation, or other uses.

[0101] It should be noted that the thermal mass composition M is a non-flowing, stationary / confined mass inside the TES vessel 130 and is not pressurized since the interior cavity 135 of the TES vessel is at atmospheric pressure. Thus, the tubes 211 of the tube bundle 210 form a pressure boundary for the heat transfer fluid flowing therethrough and are heated and pressurized by the thermal mass composition.

[0102] At least one manway 240 is provided in each header to provide access to the top and bottom headers 201, 203 of each heat exchanger 200. The manway includes an openable hatch 241 hinged to the vertical shells of the headers 201, 203. The hatch is configured to fluidly seal the access opening to the header by including an appropriate gasket material. Because heat exchanger tubes often crack and leak over time due to temperature and pressure cycling, the manway 240 allows personnel easy access to the upper tubesheet 202 or lower tubesheet 204 for maintenance, such as plugging leaking tubes in the tubesheets, or for routine inspection of the tubesheets for cracks in the tube ligaments.

[0103] The TES vessel 130 further includes a plurality of fill ports 245 at the top that extend through the top closure plate 136. The fill ports allow for the addition of thermal mass composition M to the vessel's interior cavity 135. In one embodiment, four fill ports are provided, one located at each top corner of the vessel (see, for example, FIG. 5). Each fill port may comprise a short section of capped tubing in fluid communication with the vessel's interior cavity 135, as shown.

[0104] It should be noted that the internal cavity 135 of the TES vessel 130 defines a common space or volume shared by the tube bundles 210 of all heat exchangers 200. Thus, the outer surfaces of the heat transfer tubes 211 of each heat exchanger are in direct physical and conformal contact with the same undivided / unsegregated bed of thermal mass composition M within the cavity 135. Advantageously, this ensures that the heat transfer fluid flowing through the tube side of each heat exchanger 200 is uniformly heated by a single thermal mass. Thus, there are no physical partitions or dividers subdividing the vessel's internal cavity 135, thereby further reducing manufacturing costs. In contrast, the tube sides of the heat exchangers are fluidly isolated from one another, as described elsewhere herein.

[0105] Components of the heat exchanger 200, such as the top header 202, the bottom header 204, and the tubes 211, are entirely of metallic construction. These components are preferably made of steel, and more preferably, at least in the wetted portions, of a suitable corrosion-resistant metal such as stainless steel. However, other types of tube materials can be used. The appropriate type of tube material can be selected for compatibility and usability with the particular type of thermal mass composition M used, and can be corrosion-resistant due to at least the chemical nature of the phase-change component of the material. Other metallic materials can also be used for the heat exchanger components, depending on the particular application.

[0106] The TES vessel 130 further comprises an array of immersion heaters 150 embedded in the thermal mass composition M held within the vessel's interior cavity 135 (see, e.g., FIGS. 5, 17-19, and 25). The heaters, in one non-limiting embodiment, are electric and configured to be electrically connected to an available power source, such as via any suitable commercially available electrical contacts or connectors required for the intended application. The power source can be a local power source, such as a regional power grid controlled by a utility and / or a power plant that generates electricity using renewable energy sources (such as solar, wind, biomass, etc.) or nuclear power. The heaters 150 convert electrical power received from any type of power source into thermal energy that is used to heat the thermal mass composition.

[0107] In other embodiments, instead of electric heaters, heaters 150 may each be configured as a tubular heat exchanger that circulates a second heat transfer fluid through heat exchanger tubes embedded in the thermal mass composition M of TES vessel 130 in the same location and insertable / removable slide-in unit configuration as the illustrated electric heaters. The second heat transfer fluid may be a liquid, such as water, glycol, liquid salt, or other heat transfer fluid.

[0108] In one embodiment, the heaters 150 can each have a modular structure including a panel- or box-shaped heater housing 151 and multiple horizontally elongated heating elements 170 mounted thereto. The housing 151 is configured to support the heating elements, forming a freestanding heater that can be handled and installed / removed as a single unit. In one embodiment, the housing 151 can include multiple horizontally spaced heating element support plates 151-2, each plate having a hole formed therein for receiving and supporting a horizontally elongated element (see, e.g., FIG. 20 ). The housing 151 can have a rectangular parallelepiped configuration in one embodiment, as shown, although other polygonal or non-polygonal (e.g., cylindrical) heater housing shapes are also possible. The heating elements 170 can be horizontally oriented and rod-shaped. Each element is in direct physical contact with the thermal mass composition M within the interior cavity 135 of the TES vessel 130. The heating elements can have a cylindrical configuration in one non-limiting embodiment.

[0109] The heaters 150 are removably and slidably insertable horizontally into the TES vessel interior cavity 135 between the vertical heat exchanger tubes 211 of the tube bundles 210 of each heat exchanger 200 (see, e.g., FIGS. 19-21 and 25). In one non-limiting arrangement, banks of heaters 150 may be provided on two opposing sidewalls 133 of the TES vessel 130. The units 150 are vertically and horizontally spaced apart from one another on each sidewall, as shown. A sufficient number of heaters 150 are provided and distributed across substantially the entire height of the TES vessel interior cavity 135 and the bed of thermal mass composition M contained therein to uniformly heat the bed of material from top to bottom. In one embodiment, each heater 150 can have a horizontal width greater than 40% of the width of the TES vessel housing 134 measured between the opposing sidewalls 133. Thus, the width of each heater 150 is slightly less than half the width of the vessel housing, and preferably equal to or greater than the horizontal / lateral extent of each heat exchanger tube bundle 210, to ensure that the thermal mass composition adjacent each heat exchanger tube 211 of the bundle is adequately heated by the heater's heating elements 152 (see, e.g., FIG. 25). As shown, pairs of heaters 150 may be positioned in end-to-end relationship at each elevation of the vessel 130 in which the heaters are located, with each unit entering from one of two opposing vessel side walls 133. Any suitable number of heaters 150 may be provided to sufficiently heat the thermal mass composition M to a desired maximum temperature Tmax, which determines the maximum temperature to which the heat transfer fluid flowing through the heat exchanger tubes 211 embedded in the thermal mass can be heated.

[0110] The heater 150 can be removably coupled to the side plate 133-1 of the opposing TES vessel sidewall by any suitable fastening means, including, for example, but not limited to, welding, screw fasteners, or other methods. As best shown in FIG. 21 , complementary configured mounting holes 153 are provided in the TES vessel housing 134 (i.e., the side plate 133-1 of the sidewall 133) to allow the elongated heating element 152 of the heater 150 to slide into the vessel's interior cavity 135 and become embedded in the thermal mass composition. Thermal mass composition M can be added to the vessel's interior cavity after the heater 150 is installed incrementally at each height from the bottom to the top of the vessel. Other methods of installing the heater and thermal mass composition can also be used. A relatively intimate interface is preferably provided between the vessel housing mounting holes 153 and the outermost exposed portion of the heater housing 151 that projects laterally / horizontally outward from the sidewall 133 of the TES vessel 130. The exposed portion of each heater housing 151 comprises a weatherproof junction box 151-1 which may contain conventional electrical wiring connectors (not shown) for electrically connecting the heater to a power source.

[0111] When the heater is installed in the thermal energy storage vessel 130, a thermal mass composition, which generally consists of granular solid particles in an unheated state, fills the gaps between the heating element 152 and the heat exchanger tubes 211 before the heating element is energized. When the heating element is energized, the formerly granular solid phase change material (PCM) particles melt and convert to a flowable liquid or molten state, filling the interstitial spaces between the unmelted components of the thermal mass composition (i.e., a metallic material, as further described herein). The thermal mass composition is in direct conformal contact with the heating element 152 and the tubes 211, maximizing heat transfer to the heat transfer fluid flowing within the tubes 211 of the heat exchanger 200.

[0112] In other embodiments, instead of electric heaters, the heaters 150 may each be configured as modular tube-immersed heat exchanger units 150' that circulate a second heat transfer fluid through heat exchange tubes 152' embedded in the thermal mass composition M of the TES vessel 130, in the same position and insertable / removable slide-in structure as the illustrated electric heaters. FIG. 30 shows the immersed heat exchanger units 150' arranged as a bank of heaters on opposite sides of the TES vessel housing, similar to the electric heaters previously described herein. The second heat transfer fluid may be water, glycol, molten / liquid salt, heat transfer oil, or any other suitable flowable liquid used to heat the thermal mass composition. In some embodiments, the second heat transfer fluid is heated by solar energy in a solar thermal collector and circulates in a flow loop between the collector and the TES vessel, as previously described herein. In still other embodiments, steam flows through the inner tube side of the heat exchanger tubes 152' from a steam generator that converts water to steam using any type of fuel.

[0113] Each immersion heat exchanger unit 150' can have the same type of modular construction as the electric heater, allowing it to be inserted and removed from the TES vessel 130 in a manner similar to the electric heater shown in FIG. 20. This allows the heat exchanger unit to be quickly replaced and replaced with a new unit for maintenance in the event of a tube leak, advantageously minimizing downtime of the TES vessel for heating the heat transfer fluid. Each heat exchanger unit 150' also comprises a straight panel or box-shaped heater housing 151', which includes a tube bundle 171 that is attached to the housing and includes multiple horizontally elongated heat exchanger tubes 172 embedded in a thermal mass composition. Thus, the tubes of the tube bundle are directly exposed to and in direct intimate contact with the thermal mass composition within the TES vessel 130 (i.e., there is no intervening outer metal shell as in a shell-and-tube heat exchanger). In another possible embodiment, a horizontally elongated cylindrical heat exchanger housing may be used. The housing 151' is configured to support the tubes in a manner that forms a freestanding heater that can be handled and installed / removed as a single unit.

[0114] In one embodiment, and continuing to refer to FIG. 30 , the heat exchanger housing 151′ can include a plurality of horizontally spaced tube support plates 173, each having a hole formed in it for receiving and supporting a tube. The tubes 172 are U-shaped in some embodiments and include a plurality of U-shaped tube bends 172-1 that return the second heat transfer fluid to a heat exchanger channel box 174, replacing the external weatherproof junction box 151-1 of the electric heater. The channel box 174 is internally configured to form an inlet flow plenum 174-1 that distributes hot heat transfer fluid to the tubes for heating the thermal mass composition M within the TES vessel 130, and an outlet flow plenum 174-2 configured to receive the cold heat transfer fluid after rejecting heat from the tubes to the thermal mass. Suitable conventional segmented heat exchanger channels, such as channel boxes typically used in combination with U-shaped tube bundles in heat exchanger technology, can be used without further explanation to those skilled in the art.

[0115] The housing 134 is heavily insulated to retain the heat of the thermal mass composition M within the TES vessel 130. Figure 23 shows the TES vessel in an insulated state, including an outer layer of insulation material 160 wrapped around the vessel sidewall 133. Other portions of the vessel may be insulated as needed (e.g., the exposed portion of the top plate, etc.).

[0116] It should be noted that the downcomer piping 214, previously shown in Figures 4-5 (and others), is not visible in Figure 23 and is embedded beneath the insulation 160 to retain the heat of the heat transfer fluid circulating through the downcomer from the top header 201 to the bottom header 203. Commercially available insulation of the appropriate type and thickness can be used for this application. Selecting the appropriate type and thickness of insulation is within the ability of one skilled in the art. To maintain the functionality of the insulation, commercially available corrugated metal siding panels (not shown) can also be applied over the insulation 160 for protection.

[0117] The thermal mass composition M will now be further explained.

[0118] Any suitable thermal mass composition M may be used that can be customized and selected for the heat load and operating parameters required to heat the heat transfer fluid (which may be a water / water mixture or other fluid) from the inlet temperature entering the TES (thermal energy storage) vessel 130 to the desired outlet temperature. In one embodiment, the thermal mass composition may be, but is not limited to, a mixture of at least one first base metallic material and a second phase change material (PCM). Both the base metallic material and the PCM of the thermal mass composition mixture are in granular particulate form (i.e., solid) at room temperature and can be flowed to fill the TES vessel's interior cavity 135 through an openable fill port 245 (see, for example, FIG. 5 ) through the vessel housing 134. Both the base metallic material and the PCM are materials with properties configured to absorb and store heat, creating a thermal mass configured to release that heat on demand when needed to heat the heat transfer fluid flowing through the tubes 211 of the tube bundles 210 of each heat exchanger 200.

[0119] Preferably, the at least one base metallic material comprises the majority of the mixture or composition and has a melting point or melting temperature, Tbm, that is higher than the melting point or melting temperature, Tpcm, of the PCM. The temperature, Tpcm, is preferably lower than the normal operating temperature, Tnm, of the thermal mass composition, M, to which the mass is heated for normal operation (via heat or thermal energy supplied by heater 150) so that, when the thermal mass is heated, the PCM melts and changes to a liquid or molten state. At ambient temperature, the PCM is in a solid particulate state.

[0120] In contrast, the at least one base metallic material preferably has a melting point Tbm greater than the normal operating temperature Tmm and preferably greater than the maximum temperature Tmax of the thermal mass composition when heated by the heater, so that the base metallic material always remains in a solid particulate state, regardless of whether the heater is fully energized or offline. In some representative, but non-limiting, examples, the base metallic material may have a melting point Tbm greater than 1,000°C (Celsius), or in some embodiments, greater than 2,000°C, while the PCM may have a melting point Tpcm less than 1,000°C. The metallic material may be composed of a single ferrous and / or non-ferrous metallic particle, or a combination thereof, selected to optimize heat retention capabilities and meet the aforementioned melting point criteria.

[0121] When used to store thermal energy, the TES vessel 130 (i.e., the interior cavity 135) is first filled with the thermal mass composition M to a final height or level that at least covers the highest or top heater 150 within the vessel. Both the at least one base metallic material and the PCM are in a solid, granular particle state at ambient temperature before the thermal mass is heated by the electric heater 150. When the heater 150, initially in its "off" state, is energized, the entire bed of thermal mass composition M is heated to a normal operating temperature Tnm (possibly lower than a maximum temperature Tmax). While the at least one base metallic material remains in solid, granular particle form, the PCM melts and flows, filling the interstitial spaces / voids between the base metallic material particles. This advantageously results in more efficient and complete heating of the thermal mass composition M than using an all-metal material because the air-filled pockets or voids between the material particles are filled with the conductive liquid PCM, thereby improving the heat retention properties of the thermal mass. Viewed another way, this can be thought of as somewhat analogous to wet sand where the voids between the sand particles are filled with water. The combination of the molten PCM with the still-solid base metal material particles further allows the thermal mass composition mixture to make conformal contact with both the heating element 152 of the heater 150 and the outer surface of the heat transfer tubes 211 of each heat exchanger 200, thereby further enhancing heat transfer. When the heater 150 is turned off and the heat input is removed from the thermal mass composition, the PCM returns to a solid state.

[0122] In a preferred, non-limiting embodiment, the PCM used may be a salt that can be converted from a granular solid particle state at room temperature to a liquid / molten state when heated by an immersion electric heater 150 energized by power drawn from an available power source, such as the electrical grid or other source. Any suitable salt selected to suit the required heat load may be used.

[0123] Some examples of salts that can be used to form the PCM bed B in each thermal energy storage vessel 121 are listed in the following table: TIFF2025531277000002.tif161154

[0124] The melting temperature and latent heat properties of the salt are important characteristics and factors in selecting the type of salt depending on the required heat load and temperature rise of the heat transfer fluid. It should be noted that the type of salt used in each thermal energy storage vessel 130 of the green boiler 120 can be customized and can vary. It will be apparent to those skilled in the art that the heat load and performance of the thermal energy storage vessel 121 can be highly customized to meet the required temperature rise target of the thermal energy system, whether the application is simply heating water for district heating or other applications.

[0125] It should be noted that any suitable PCM other than the salts listed above can be used, provided that the melting point, Tpcm, of the PCM is lower than the normal operating temperature, Tnm (described earlier in this specification), of the thermal mass composition during operation of the TES vessel 130 when the heater 150 is energized.

[0126] The thermal energy storage (TES) vessel 130121 disclosed herein is described in a non-limiting manner as being for heating water to a high temperature liquid or vapor phase via a thermal mass composition bed for various purposes and applications, although the invention is not limited in this respect. Thus, the TES vessel 130 can be used to heat any type of fluid that can pass through the vessel's heat exchanger tubes 211. Thus, numerous applications of the "green" thermal energy storage system 100 are possible and are within the scope of this disclosure.

[0127] The general operation of the TES vessel 130 to store thermal energy and heat the heat transfer fluid can be summarized as follows: The process or method can begin with the thermal mass composition M being depleted of sufficient thermal energy to heat the heat transfer fluid to the desired operating conditions (e.g., pressure and temperature). This can occur prior to operating the TES vessel 130 by operating and releasing thermal energy from the thermal mass, or after a period of time, or upon initial start-up. At this point, the TES vessel 130 can be fluidly isolated from the closed flow loop 110 (see FIGS. 1B or 1C) by closing the inlet valve 219 and outlet valve 212-1 shown in FIG. 22.

[0128] The bank of electric immersion heaters 150 is then energized, preferably during off-peak demand periods when energy costs are lowest, by drawing power from the grid (or other power source) if possible, or by other power sources. Power is applied to the heaters until the thermal mass composition M is heated to its normal operating temperature, Tnm, and has optimal heat retention capacity. Power is then removed from the power source. The thermal mass composition is now fully thermally charged and is in a standby state, ready to operate when needed to generate steam or hot water (or other heated heat transfer fluid) as required by the thermal energy system of Figures 1B or 1C. During this standby period, heat transfer fluid circulates through the heat exchanger tube bundles 210 and the TES vessel 130 via the downcomer pipe 214, which forms a vessel circulation flow loop.

[0129] When it is desired to begin operation of the TES vessel 130, the inlet valve 219-1 and the outlet valve 212-1 are opened. This initiates the flow of heat transfer fluid from the closed flow loop 110 through the vessel and the bed of thermal mass composition in the tubes 211 of one or more heat exchangers 200. The heat transfer fluid is heated to an operating temperature and pressure by thermal energy released from the thermal mass composition, as described elsewhere herein. It should be noted that, if steam is produced, the steam is produced by the TES vessel 130 at a saturated state for low-pressure steam applications (e.g., industrial applications or steam heating) or at a superheated state for power generation via a Rankine cycle system, as shown in FIG. 1B. The heat transfer surface area of ​​the tubes 211 in the heat exchanger tube bundle 210 and the composition of the thermal mass composition can be designed and customized to provide the necessary heating of the heat transfer fluid to the desired operating temperature and pressure.

[0130] Once the available thermal energy stored in the thermal mass composition is depleted or the end-use demand no longer requires operation of the TES vessel 130 and heating of the heat transfer fluid, the vessel inlet and outlet valves 219-1, 212-1 can be closed again. The foregoing operating cycle can be repeated as many times as necessary based on the demand for steam or heated liquid heat transfer fluid (e.g., water or other heat transfer medium).

[0131] The thermal energy storage system 100 of the present invention is advantageously modular in nature. In other words, multiple thermal energy storage (TES) vessels 130 can be provided at any installation to meet the design and operational requirements of the facility, which uses them to heat a heat-transfer fluid via the thermal energy stored in the thermal mass composition M within each vessel. Potential applications for the system include the production of hot water (or water mixtures, such as glycol and water) for district heating, industrial processes, or other heated liquid applications, and the production of steam for steam heating, industrial processes, power generation, or other applications. The number of TES vessels 130 deployed is selected to produce heat-transfer fluid in a liquid or gaseous (e.g., steam) state at a volume / quantity and temperature sufficient to meet the needs of the intended application. Furthermore, the modular system can be used to add extra heat-transfer fluid heating capacity over time as demand increases, such as with increasing population and infrastructure (e.g., housing) in district heating or other applications.

[0132] To facilitate maintenance of the heat exchanger 200 of the green boiler 120, the TES vessel 130 may further include a penthouse structure 165, shown only in Figures 2 and 3. Only the structural framework of the penthouse structure is shown to better illustrate and clarify the upper header 201 of the heat exchanger 200. The penthouse structure includes conventional metal siding, roof panels, and, if necessary, insulation that encloses the interior space, thereby protecting operators and maintenance workers from the components during inclement weather.

[0133] A method or process for heating a heat transfer fluid using a green boiler 120 is described and summarized below. The method includes providing a thermal energy storage container 130 containing a thermal mass composition M including a mixture of a metallic material and a phase change material, each initially in the form of solid particles. The metallic material has a higher melting point than the phase change material. The method involves heating the thermal mass composition to a temperature at which the phase change material melts, while the metallic material remains as solid particles. The method continues to store heat in the thermal mass composition. The method continues to heat the heat transfer fluid by circulating a heat transfer fluid through the thermal mass composition. The heating step can include energizing a plurality of electric heaters embedded in the thermal mass composition. The circulating step can include flowing the heat transfer fluid through a tube bundle embedded in the thermal mass composition. The tube bundle can be part of at least one heat exchanger 200 incorporated into the thermal energy storage container. The heated heat transfer fluid can be in liquid or vapor form. The heating step may further include causing the molten phase change material to flow into and fill interstices between the solid particles of the metallic material.

[0134] Illustrative Claim Summary Below are exemplary claims supported by this disclosure for the invention(s) described herein.

[0135] (Exemplary Claim 1) A green boiler, a thermal energy storage container defining an interior space containing a thermal mass composition operable to store thermal energy, the thermal mass composition comprising a metallic material and a phase change material; at least one heater embedded in the thermal mass composition, the at least one heater configured to be operable to heat the thermal mass composition; and at least one heat exchanger comprising a tube bundle including a plurality of heat exchanger tubes embedded in the thermal mass composition, the heat exchanger tubes configured to transport a heat transfer fluid through the thermal mass composition to heat the heat transfer fluid; A boiler comprising:

[0136] (Example claim 2) 10. The boiler of claim 1, wherein the thermal energy storage vessel and the at least one heater are physically integrated within a single, self-contained housing.

[0137] (Example claim 3) 10. The boiler of claim 2, wherein the housing comprises a top closure plate, a bottom closure plate, and a plurality of side walls extending therebetween.

[0138] (Example claim 4) 10. The boiler of claim 2, wherein the housing comprises a support base configured to be placed on a flat concrete foundation slab.

[0139] (Example claim 5) 5. The boiler according to claim 2, wherein the housing is elongated in the vertical direction and has a rectangular parallelepiped shape.

[0140] (Example claim 6) Exemplary claim 3 is a boiler, characterized in that the heat exchanger comprises an upper header supported on the upper closure plate and defining an upper flow plenum, and a bottom header supported on the bottom closure plate and defining a bottom flow plenum, the upper flow plenum and the lower flow plenum being in fluid communication with heat exchanger tubes within the housing.

[0141] (Example claim 7) 10. The boiler of claim 6, wherein the heat exchanger further comprises an upper tube sheet supported on the upper closure plate in the upper flow plenum, and a bottom tube sheet supported on the bottom closure plate in the bottom flow plenum.

[0142] (Example claim 8) 10. A boiler as described in exemplary claim 7, wherein upper ends of the tubes are connected to and pass through the upper tube sheet, and lower ends of the heat exchanger tubes are connected to and pass through the bottom tube sheet.

[0143] (Example claim 9) 10. The boiler of claim 8, wherein the upper tube sheet further comprises a plurality of extension tubes projecting upward, each extension tube being fluidly coupled to and associated with one of the heat exchanger tubes.

[0144] (Example claim 10) 10. A boiler as described in claim 9, wherein the upper end of the extension tube terminates at a height higher than the surface level of the condensate pool P formed in the upper flow plenum in the upper header.

[0145] (Example claim 11) Exemplary claim 8 is a boiler, wherein the housing further comprises an annular thermal expansion sleeve fixedly connected to the upper closure plate, the sleeve circumferentially surrounding the upper sheet and a lower portion of the upper header, which are slidably disposed inside the sleeve.

[0146] (Example claim 12) 12. A boiler as described in exemplary claim 11, characterized in that when the heat exchanger tubes are heated and expand in length, the upper sheet and the upper header move upward together with the upper ends of the heat exchanger tubes relative to the upper closure plate which remains stationary.

[0147] (Example claim 13) An exemplary boiler as described in any one of claims 6 to 12, characterized in that the upper flow plenum is fluidly connected to the bottom flow plenum by a vertical downcomer arranged outside the housing.

[0148] (Example claim 14) 14. A boiler as described in exemplary claim 13, wherein the heat transfer fluid circulates between the upper flow plenum and the bottom flow plenum through the downcomer by thermal convection siphon effect without the aid of a pump.

[0149] (Example claim 15) 10. The boiler of claim 3, wherein the at least one heater comprises a plurality of heaters, each heater comprising a horizontally elongated electric heating element extending within the thermal mass composition within the vessel.

[0150] (Example claim 16) 16. A boiler as described in exemplary claim 15, wherein the heater is removably coupled to a pair of opposing side walls of the housing, and the heater can be horizontally slidably inserted and withdrawn into the internal cavity of the vessel.

[0151] (Example claim 17) 10. The boiler of claim 1, wherein the heat transfer fluid comprises water.

[0152] (Example claim 18) 18. The boiler of claim 17, wherein the vessel is configured to convert the water from a liquid state entering the vessel to steam exiting the vessel.

[0153] (Example claim 19) 18. A boiler as described in exemplary claim 17, wherein the vessel is configured to receive 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.

[0154] (Example claim 20) 20. A boiler according to any one of claims 1 to 19, characterized in that the thermal mass composition comprises a mixture of a metal material and a phase change material, each of which is in the form of solid particles at room temperature.

[0155] (Example claim 21) 21. Exemplary boiler according to claim 20, wherein the metallic material has a higher melting point than the phase change material.

[0156] (Example claim 22) 10. The boiler of claim 3, wherein the at least one heater comprises a horizontally elongated heat exchange tube extending within the thermal mass composition within the vessel, the heat exchange tube passing a heated second heat transfer fluid through the tube to heat the thermal mass composition.

[0157] (Example claim 23) 23. A boiler as described in exemplary claim 22, wherein the heater is removably coupled to the pair of opposing side walls of the housing, and the heater can be horizontally slidably inserted and withdrawn into the internal cavity of the vessel.

[0158] (Example claim 24) 1. A method for heating a heat transfer fluid via thermal energy storage, comprising: providing a thermal energy storage container having a thermal mass composition including a mixture of a metallic material and a phase change material, each in the form of solid particles, the metallic material having a higher melting point than the phase change material; heating the thermal mass composition to a temperature between the melting point of the metallic material and the melting point of the phase change material, thereby melting the phase change material while the metallic material remains in a solid state; storing heat in the thermal mass composition; circulating a cold heat transfer fluid through the thermal mass composition; the heat transfer fluid drawing heat from the thermal mass composition heating the heat transfer fluid; A method for providing the above.

[0159] (Example claim 25) 25. The method of claim 24, wherein the heating step comprises energizing a plurality of electric heaters embedded in the thermal mass composition.

[0160] (Example claim 26) 26. The method of exemplary claim 24 or 25, wherein the phase change material is a salt.

[0161] (Example claim 27) 27. The method of claim 26, wherein the heating step includes causing the molten phase change material to flow and fill interstitial spaces between the solid particles of the metallic material.

[0162] (Example claim 28) 26. The method of exemplary claim 24 or 25, wherein the heated heat transfer fluid is liquid heated water.

[0163] (Example claim 29) 30. The method of claim 28, further comprising the step of flowing the heated water through a district heating flow distribution network.

[0164] (Example claim 30) 26. The method of exemplary claim 24 or 25, wherein the heated heat transfer fluid is water in steam form.

[0165] (Example claim 31) 31. The method of claim 30, further comprising the step of channeling the steam through a turbine generator set configured to generate electricity.

[0166] (Example claim 32) 26. The method of claim 24 or 25, wherein the circulating step comprises flowing the heat transfer fluid through tube bundles embedded in the thermal mass composition.

[0167] (Example claim 33) 33. The method of claim 32, wherein the tube bundle is part of a heat exchanger.

[0168] (Example claim 34) An exemplary method according to any one of claims 24 to 33, further comprising a step of mixing and circulating a portion of the heated heat transfer fluid discharged from the container with the cold heat transfer fluid entering the container.

[0169] (Example claim 35) 35. The method of claim 24, wherein the vessel is vertically elongated and includes an upper flow plenum for receiving the heated heat transfer fluid from the tube bundle and a lower flow plenum for receiving the cold heat transfer fluid before it enters the tube bundle.

[0170] (Example claim 36) 36. The method of claim 35, further comprising circulating a portion of the heated heat transfer fluid removed from the upper flow plenum and mixing the portion with colder heat transfer fluid before it enters the bottom flow plenum.

[0171] (Example claim 37) 1. A thermal energy storage and power generation system comprising: a closed flow loop comprising a steam turbine generator assembly, a steam condenser, and a boiler in fluid communication therewith, and a pump for circulating boiler feedwater through the closed flow loop; a generator operatively connected to the steam turbine and to an electric power grid; Equipped with The boiler comprises: a thermal energy storage container containing a thermal mass composition therein; an array of electric heaters embedded in the thermal mass composition, the heaters operative to heat the thermal mass composition when energized; a tube bundle comprising a plurality of heat exchanger tubes embedded in the thermal mass composition, the heat exchanger tubes configured to pump boiler feedwater therethrough; and Equipped with The system is configured to receive boiler feedwater in a liquid state and heat it with the thermal mass composition in the vessel to produce steam, which then flows through a closed flow loop to a steam turbine to generate electricity.

[0172] (Example claim 38) 38. The system of exemplary claim 37, wherein the thermal mass composition comprises a mixture of a metallic material and a phase change material, each in the form of solid particles, before the heater is energized.

[0173] (Example claim 39) 39. The system of exemplary claim 38, wherein the metallic material has a higher melting point than the phase change material, such that the metallic material remains as solid particles when the thermal mass composition is heated by the heater.

[0174] (Example claim 40) 40. The system of claim 38 or 39, wherein the phase change material is meltable when the thermal mass composition is heated by the heater, and the melted phase change material is capable of flowing into interstitial spaces between solid particles of the metal material.

[0175] (Exemplary claim 41) 41. The system according to any one of claims 38 to 40, wherein the phase change material is a salt.

[0176] (Example claim 42) 38. The system of exemplary claim 37, wherein the heater is an immersion-type electric heater electrically connected to a power source.

[0177] (Example claim 43) 38. The system of claim 37, wherein the heater is an immersion heat exchanger that flows a heat transfer fluid through tubes of the immersion heat exchanger embedded in the thermal mass composition.

[0178] (Example claim 44) A green boiler, a thermal energy storage vessel defining an interior space having a thermal mass composition operable to store thermal energy; at least one heater embedded in the thermal mass composition, the heater configured to heat the thermal mass composition; a plurality of heat exchangers each comprising a tube bundle including a plurality of heat exchanger tubes embedded in the thermal mass composition, the heat exchanger tubes transporting a heat transfer fluid through the thermal mass composition heating the heat transfer fluid; Equipped with A green boiler characterized in that the plurality of heat exchangers are operable independently of each other.

[0179] (Example claim 45) 45. A green boiler as described in exemplary claim 44, wherein each heat exchanger has a fluid outlet controlled by an associated fluid outlet valve and a fluid inlet controlled by an associated return fluid inlet valve, each fluid outlet valve and return fluid inlet valve being selectively openable and closable to fluidly couple or fluidly isolate one heat exchanger from the other heat exchanger, respectively.

[0180] (Exemplary claim 46) 46. ​​The green boiler of exemplary claim 45, further comprising: a discharge piping network fluidly coupled to each fluid outlet valve and configured to combine heated heat transfer fluid exiting each heat exchanger into a single stream; and an inlet piping network fluidly coupled to each return fluid inlet valve and configured to distribute incoming cold heat transfer fluid to each heat exchanger.

[0181] (Example claim 47) 45. A green boiler as described in exemplary claim 44, wherein the heated heat transfer fluid discharged from each heat exchanger is steam, and the discharge piping network is fluidly coupled to a steam storage tank configured to store the steam.

[0182] (Exemplary claim 48) 47. A green boiler as described in exemplary claim 46, wherein the discharge piping network includes a piping manifold configured to receive and combine heated heating fluid from each heat exchanger.

[0183] (Example claim 49) 46. ​​A green boiler as described in exemplary claim 45, wherein each fluid outlet valve is independently connected directly to the steam storage tank via a fluid outlet pipe.

[0184] (Example claim 50) 50. A green boiler as claimed in any one of claims 44 to 49, wherein each heat exchanger includes a top header fluidly coupled to the tubes of a respective tube bundle and a bottom header fluidly coupled to the tubes of a respective tube bundle, and the top header and the bottom header of each heat exchanger are fluidly isolated from the top headers and bottom headers of the other heat exchangers.

[0185] (Exemplary claim 51) 51. The green boiler of exemplary claim 50, wherein the tubes of each tube bundle extend vertically between the top header and the bottom header of each heat exchanger.

[0186] (Exemplary claim 52) 45. A green boiler according to exemplary claim 44, comprising: A green boiler characterized in that one heat exchanger is disposed in each of the four quadrants of the thermal energy storage vessel, forming four fluid heating zones.

[0187] (Example claim 53) 1. A method of operating a green boiler for heating a heat transfer fluid via storage of thermal energy, comprising: providing a thermal energy storage vessel having a thermal mass composition operable to store thermal energy; providing a plurality of heat exchangers each comprising a tube bundle including a plurality of heat exchange tubes embedded in the thermal mass composition, each heat exchanger including a fluid inlet valve and a fluid outlet valve fluidly coupled to the tube bundle; heating the thermal mass composition; selectively activating one or more of the plurality of heat exchangers and flowing a heat transfer fluid through the tube bundles of the activated heat exchangers to heat the heat transfer fluid by extracting heat from the thermal mass composition; Discharging the heated heat transfer fluid from the activated heat exchanger; A method for providing the above.

[0188] (Exemplary claim 54) 54. The method of claim 53, further comprising combining the separate discharge streams of heated heat transfer fluid from each heat exchanger into a single discharge stream.

[0189] (Exemplary claim 55) 55. The method of claim 54, wherein the separate exhaust streams are combined by a piping manifold.

[0190] (Exemplary claim 56) 55. The method of exemplary claim 54, comprising: 10. The method of claim 9, wherein the heated heat transfer fluid is steam and the separate exhaust streams are combined by a steam reservoir.

[0191] (Example claim 57) A green boiler, a thermal energy storage container defining an interior cavity having a thermal mass composition operable to store thermal energy; at least one heater embedded in the thermal mass composition, the at least one heater configured to heat the thermal mass composition, and at least one heat exchanger; The green boiler is characterized by comprising:

[0192] The heat exchanger comprises: a tube bundle including a plurality of heat exchange tubes embedded in the thermal mass composition, the heat exchanger tubes transporting a heat transfer fluid through the thermal mass composition heating the heat transfer fluid; an upper header configured to receive the heated heat transfer fluid from the tube bundle; a bottom header configured to receive and distribute an incoming cold heat transfer fluid to the tubes of the tube bundle; a downcomer fluidly coupled to each of the top header and the bottom header; Equipped with.

[0193] The heat exchange tubes, the top header, the downcomer, and the bottom header form a circulation loop, and the at least one heat exchanger is configured to facilitate flow of the heat transfer fluid through the circulation loop by a thermosiphon effect. (Exemplary claim 58) 58. The green boiler of exemplary claim 57, wherein the tubes are vertically oriented and extend in a straight path between the top header and the bottom header.

[0194] (Example claim 59) 59. The green boiler of exemplary claim 58, wherein the downcomer extends vertically from the top header to the bottom header, and the downcomer is positioned outside the thermal mass composition.

[0195] (Exemplary claim 60) 60. A green boiler according to any one of claims 57 to 59, wherein the top header and the bottom header are arranged outside the thermal mass composition.

[0196] (Exemplary claim 61) 61. A green boiler as described in any one of exemplary claims 57 to 60, wherein the heated heat transfer fluid is steam, and the upper header includes a demister configured to condense excess moisture in the steam that collects in the upper header and returns to the bottom header through the downcomer.

[0197] 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 thereto without departing from the spirit and scope of the appended claims and their range 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, sizes, and other elements, materials, and components without departing from the spirit or essential characteristics thereof. Furthermore, numerous variations can be made to the methods / processes described herein within the scope of the present disclosure. Those skilled in the art will further understand that the embodiments can be used with many changes in the structure, arrangement, proportions, sizes, materials, and components used to implement the present disclosure to adapt them to particular environments and operating requirements without departing from the principles described herein. Therefore, the presently disclosed embodiments should be considered in all respects as illustrative and not restrictive. The appended claims should be interpreted broadly to include modifications and embodiments other than those disclosed herein that can be made by those skilled in the art without departing from the range of equivalents.

Claims

1. A green boiler, a thermal energy storage container defining an interior space containing a thermal mass composition operable to store thermal energy, the thermal mass composition comprising a metallic material and a phase change material; at least one heater embedded in the thermal mass composition, the at least one heater configured to be operable to heat the thermal mass composition; and at least one heat exchanger comprising a tube bundle including a plurality of heat exchanger tubes embedded in the thermal mass composition, the heat exchanger tubes configured to transport a heat transfer fluid through the thermal mass composition heating the heat transfer fluid; A boiler comprising:

2. 10. The boiler of claim 1, wherein the thermal energy storage vessel and the at least one heater are physically integrated within a single, self-contained housing.

3. 3. The boiler of claim 2, wherein the housing comprises a top closure plate, a bottom closure plate, and a plurality of side walls extending therebetween.

4. 3. The boiler of claim 2, wherein the housing comprises a support base configured to rest on a flat concrete foundation slab.

5. 5. The boiler according to claim 2, wherein the housing is elongated in the vertical direction and has a rectangular parallelepiped shape.

6. 4. The boiler of claim 3, wherein the heat exchanger comprises an upper header supported by the upper closure plate and defining an upper flow plenum, and a bottom header supported by the bottom closure plate and defining a bottom flow plenum, the upper flow plenum and the lower flow plenum being in fluid communication with the heat exchanger tubes within the housing.

7. 7. The boiler of claim 6, wherein the heat exchanger further comprises an upper tube sheet supported on the upper closure plate in the upper flow plenum, and a bottom tube sheet supported on the bottom closure plate in the bottom flow plenum.

8. 8. The boiler of claim 7, wherein upper ends of the tubes are connected to and pass through the upper tube sheet, and lower ends of the heat exchanger tubes are connected to and pass through the bottom tube sheet.

9. 9. The boiler of claim 8, wherein the upper tube sheet further comprises a plurality of upwardly projecting extension tubes, each extension tube being fluidly coupled to and associated with one of the heat exchanger tubes.

10. 10. The boiler according to claim 9, wherein the upper end of the extension pipe terminates at a height higher than the surface level of a condensate pool P formed in the upper flow plenum in the upper header.

11. 9. The boiler according to claim 8, wherein the housing further comprises an annular thermal expansion sleeve fixedly connected to the upper closure plate, the sleeve circumferentially surrounding the upper sheet and a lower portion of the upper header, the upper sheet being slidably disposed inside the sleeve.

12. 12. The boiler of claim 11, wherein when the heat exchanger tubes are heated and expand in length, the upper sheet and the upper header move upward with the upper ends of the heat exchanger tubes relative to the upper closure plate, which remains stationary.

13. 13. The boiler of claim 6, wherein the upper flow plenum is fluidly coupled to the bottom flow plenum by a vertical downcomer disposed outside the housing.

14. 14. The boiler of claim 13, wherein the heat transfer fluid circulates between the upper flow plenum and the bottom flow plenum through the downcomer by passive thermal convection siphon effect without the aid of a pump.

15. 4. The boiler of claim 3, wherein the at least one heater comprises a plurality of heaters, each heater comprising a horizontally elongated electric heating element extending into the thermal mass composition within the vessel.

16. 16. The boiler of claim 15, wherein the heater is removably coupled to a pair of opposing side walls of the housing, and the heater is horizontally slidably insertable and removable from the interior cavity of the vessel.

17. 10. The boiler of claim 1, wherein the heat transfer fluid comprises water.

18. 18. The boiler of claim 17, wherein the vessel is configured to convert the water from a liquid state entering the vessel to steam exiting the vessel.

19. 18. The boiler of claim 17, wherein the vessel is configured to receive 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.

20. 20. The boiler of claim 1, wherein the thermal mass composition comprises a mixture of a metallic material and a phase change material, each of which is in the form of solid particles at room temperature.

21. 21. The boiler of claim 20, wherein the metallic material has a higher melting point than the phase change material.

22. 4. The boiler of claim 3, wherein the at least one heater comprises a heat exchange tube extending into the thermal mass composition within the vessel, the heat exchange tube causing a heated second heat transfer fluid to flow through the tube, the heated second heat transfer fluid heating the thermal mass composition.

23. 23. The boiler of claim 22, wherein the heater is removably coupled to the pair of opposing side walls of the housing, and the heater is horizontally slidably insertable and removable from the internal cavity of the vessel.

24. 1. A method for heating a heat transfer fluid via thermal energy storage, comprising: providing a thermal energy storage container having a thermal mass composition including a mixture of a metallic material and a phase change material, each in the form of solid particles, the metallic material having a higher melting point than the phase change material; heating the thermal mass composition to a temperature between the melting point of the metallic material and the melting point of the phase change material, thereby melting the phase change material while the metallic material remains in a solid state; storing heat in the thermal mass composition; circulating a cold heat transfer fluid through the thermal mass composition; the heat transfer fluid drawing heat from the thermal mass composition heating the heat transfer fluid; A method for providing the above.

25. 25. The method of claim 24, wherein the heating step comprises energizing a plurality of electric heaters embedded in the thermal mass composition.

26. 26. The method of claim 24 or 25, wherein the phase change material is a salt.

27. 27. The method of claim 26, wherein the heating step includes causing the molten phase change material to flow and fill interstitial spaces between the solid particles of the metallic material.

28. 26. A method according to claim 24 or 25, wherein the heated heat transfer fluid is liquid heated water.

29. 30. The method of claim 28, further comprising the step of flowing the heated water through a district heating flow distribution network.

30. 26. A method according to claim 24 or 25, wherein the heated heat transfer fluid is water in steam form.

31. 31. The method of claim 30, further comprising channeling the steam through a turbine generator set configured to generate electricity.

32. 26. The method of claim 24 or 25, wherein the circulating step comprises flowing the heat transfer fluid through tube bundles embedded in the thermal mass composition.

33. 33. The method of claim 32, wherein the tube bundle is part of a heat exchanger.

34. 34. The method of any one of claims 24 to 33, further comprising the step of mixing and circulating a portion of the heated heat transfer fluid exiting the vessel with the cold heat transfer fluid entering the vessel.

35. 34. The method of any one of claims 24 to 33, wherein the vessel is vertically elongated and includes an upper flow plenum that receives the heated heat transfer fluid from the tube bundles, and a bottom flow plenum that receives the cooler heat transfer fluid before it enters the tube bundles.

36. 36. The method of claim 35, further comprising circulating a portion of the heated heat transfer fluid removed from the upper flow plenum and mixing the portion with cooler heat transfer fluid before the portion enters the bottom flow plenum.

37. 1. A thermal energy storage and power generation system comprising: a closed flow loop comprising a steam turbine generator assembly, a steam condenser, and a boiler in fluid communication; a generator operatively connected to the steam turbine and to an electric power grid; Equipped with The boiler comprises: a thermal energy storage container containing a thermal mass composition therein; at least one heater embedded in the thermal mass composition, said heater operative to heat said thermal mass composition; a tube bundle comprising a plurality of heat exchanger tubes embedded in the thermal mass composition, the heat exchanger tubes configured to pump boiler feedwater therethrough; and Equipped with The thermal energy storage vessel is configured to receive boiler feedwater in a liquid state and heat it with the thermal mass composition in the vessel to produce steam, which then flows through a closed flow loop to a steam turbine generator to produce electricity.

38. 38. The system of claim 37, wherein the thermal mass composition comprises a mixture of a metallic material and a phase change material, each in solid particle form, before the heater is energized.

39. 39. The system of claim 38, wherein the metallic material has a higher melting point than the phase change material such that the metallic material remains as solid particles when the thermal mass composition is heated by the heater.

40. 40. The system of claim 38 or 39, wherein the phase change material is meltable when the thermal mass composition is heated by the heater, and the melted phase change material is capable of flowing into interstitial spaces between solid particles of the metallic material.

41. 41. The system according to any one of claims 38 to 40, wherein the phase change material is a salt.

42. 38. The system of claim 37, wherein the heater is an electric immersion heater electrically connected to a power source.

43. 38. The system of claim 37, wherein the heater is an immersion heat exchanger that flows a heat transfer fluid through tubes of the immersion heat exchanger embedded in the thermal mass composition.

44. A green boiler, a thermal energy storage vessel defining an interior space having a thermal mass composition operable to store thermal energy; at least one heater embedded in the thermal mass composition, the heater configured to heat the thermal mass composition; a plurality of heat exchangers each comprising a tube bundle including a plurality of heat exchanger tubes embedded in the thermal mass composition, the heat exchanger tubes transporting a heat transfer fluid through the thermal mass composition heating the heat transfer fluid; Equipped with A green boiler characterized in that the plurality of heat exchangers are operable independently of each other.

45. 45. A green boiler as described in claim 44, wherein each heat exchanger has a fluid outlet controlled by an associated fluid outlet valve and a fluid inlet controlled by an associated return fluid inlet valve, each fluid outlet valve and return fluid inlet valve being selectively openable and closable to fluidly couple or isolate one heat exchanger from the other heat exchanger, respectively.

46. 46. ​​The green boiler of claim 45, further comprising: a discharge piping network fluidly coupled to each fluid outlet valve and configured to combine heated heat transfer fluid exiting each heat exchanger into a single stream; and an inlet piping network fluidly coupled to each return fluid inlet valve and configured to distribute incoming cold heat transfer fluid to each heat exchanger.

47. 45. The green boiler of claim 44, wherein the heated heat transfer fluid discharged from each heat exchanger is steam, and wherein the discharge piping network is fluidly coupled to a steam reservoir configured to store the steam.

48. 47. The green boiler of claim 46, wherein the exhaust piping network includes a piping manifold configured to receive and combine heated heating fluid from each heat exchanger.

49. 46. ​​The green boiler of claim 45, wherein each fluid outlet valve is independently connected directly to the steam storage tank via a fluid outlet pipe.

50. 50. A green boiler according to any one of claims 44 to 49, wherein each heat exchanger includes a top header fluidly coupled to the tubes of a respective tube bundle and a bottom header fluidly coupled to the tubes of a respective said tube bundle, the top header and the bottom header of each heat exchanger being fluidly isolated from the top header and the bottom header of the other heat exchangers.

51. 51. A green boiler as claimed in claim 50, wherein the tubes of each tube bundle extend vertically between the top and bottom headers of each heat exchanger.

52. 45. A green boiler according to claim 44, A green boiler characterized in that one heat exchanger is disposed in each of four quadrants of the thermal energy storage vessel to form four fluid heating zones.

53. 1. A method of operating a green boiler for heating a heat transfer fluid via storage of thermal energy, comprising: providing a thermal energy storage vessel having a thermal mass composition operable to store thermal energy; providing a plurality of heat exchangers each comprising a tube bundle including a plurality of heat exchange tubes embedded in the thermal mass composition, each heat exchanger including a fluid inlet valve and a fluid outlet valve fluidly coupled to the tube bundle; heating the thermal mass composition; selectively activating one or more of the plurality of heat exchangers and flowing a heat transfer fluid through the tube bundles of the activated heat exchangers to heat the heat transfer fluid by extracting heat from the thermal mass composition; Discharging the heated heat transfer fluid from the activated heat exchanger; A method for providing the above.

54. 54. The method of claim 53, further comprising combining the separate exhaust streams of heated heat transfer fluid from each heat exchanger into a single exhaust stream.

55. 55. The method of claim 54, wherein the separate exhaust streams are combined by a piping manifold.

56. 55. The method of claim 54, 10. The method of claim 9, wherein the heated heat transfer fluid is steam and the separate exhaust streams are combined by a steam reservoir.

57. A green boiler, a thermal energy storage container defining an interior cavity having a thermal mass composition operable to store thermal energy; at least one heater embedded in the thermal mass composition, the at least one heater configured to heat the thermal mass composition; at least one heat exchanger, The heat exchanger comprises: a tube bundle including a plurality of heat exchange tubes embedded in the thermal mass composition, the heat exchanger tubes transporting a heat transfer fluid through the thermal mass composition heating the heat transfer fluid; an upper header configured to receive the heated heat transfer fluid from the tube bundle; a bottom header configured to receive and distribute an incoming cold heat transfer fluid to the tubes of the tube bundle; a downcomer fluidly coupled to each of the top header and the bottom header; Equipped with the heat exchange tubes, the top header, the downcomer, and the bottom header form a circulation loop; A heat exchanger; Equipped with 10. A green boiler comprising: a heat exchanger configured to facilitate flow of the heat transfer fluid through the circulation loop by a thermosiphon effect;

58. 58. The green boiler of claim 57, wherein the tubes are vertically oriented and extend in a straight path between the top header and the bottom header.

59. 59. The green boiler of claim 58, wherein the downcomer extends vertically from the top header to the bottom header, the downcomer being located outside of the thermal mass composition.

60. 60. The green boiler of any one of claims 57 to 59, wherein the top header and the bottom header are located outside the thermal mass composition.

61. 61. A green boiler according to any one of claims 57 to 60, wherein the heated heat transfer fluid is steam, and the upper header includes a demister configured to condense excess water in the steam that collects in the upper header and returns to the bottom header through the downcomer.

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