Thermal energy storage

Abstract

A thermal energy storage and exchange device 100 comprising: - an external casing 1 made of metalworking; - a particle-fluidable bed 4; - a metal separation means 3 located around the particle bed and away from the walls 5 of the external casing to create a hollow volume 20; - a certain amount of stationary particles 2 filling the hollow volume; and - a means 5 for heating the fluidized bed, wherein the metal separation means allows for airtightness of the fluidized air, and the section of stationary particles that is neither fluidized nor aerated acts as an insulator.

Description

Technical Field

[0001] The present invention relates to a thermal energy storage and release device based on a fluidizable bed of particles.

[0002] The present invention also provides an energy generation plant including such a device.

Background Art

[0003] The prior art uses thermal energy and exchange devices based on a bed of particles fluidized by adding air. In such a device, for example, a fluidized bed consisting of sand particles receives, stores, and releases such energy to a working fluid or other heat exchange means as a heat medium, either as needed or delayed, from a source of solar nature.

[0004] This type of device is described, for example, in International Publication Nos. 2011 / 135501 and 2017 / 021832 under the name of the same applicant.

[0005] Some types of plants for the generation of thermal energy and / or electrical energy can include one or more of the thermal energy storage or exchange devices acting as modules.

[0006] In known prior art fluidized bed devices, the thermal confinement of the particle bed is achieved by a casing including insulating and refractory materials placed in direct contact with the fluidized bed of particles. This involves significant costs both for the materials used and for the laying.

[0007] The refractory materials are usually resistant to wear and high temperatures, and they have expansion joints arranged within a selected area depending on the area extension and the expected operating temperature. However, at the expansion joints, cracks or fractures may occur due to the hydrostatic thrust of the particle bed, the start / stop cycle of fluidization, and operating temperatures above 600°C.

[0008] The aforementioned cracks or fissures, in particular, determine losses in the fluidized air by hindering proper fluidization, reducing heat exchange performance, and preventing the effective movement of particles.

[0009] Interventions to repair expansion joints, which are fire-resistant materials or the entire refractory structure, require shutting down the plant and emptying the particle bed, which involves associated costs and consequently, thermal energy generation losses.

[0010] Therefore, the effectiveness and performance of known fluidized bed thermal energy storage and release devices can be improved. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] International Publication No. 2011 / 135501 [Patent Document 2] International Publication No. 2017 / 021832 [Overview of the project] [Problems that the invention aims to solve]

[0012] Next, the technical problem brought about and solved by the present invention is to implement a thermal energy storage and release device that enables the avoidance of the drawbacks mentioned above by reference to known technologies by improving its effectiveness and / or performance. [Means for solving the problem]

[0013] Such problems are solved by the device described in claim 1.

[0014] Preferred features of the device of the present invention are described in the dependent claims.

[0015] The device according to the present invention is equipped with an insulating system based on a section of immobile granular particles that are a stationary floor. This section is separated from a second flowable floor by a partitioning means implemented by a metal sheet positioned away from the walls of an outer casing around the flowable floor itself, so as to create a hollow volume that actually receives the stationary floor. In such an arrangement, the metal sheet acts as a means of separation between the flowable floor of particles and the section of static particles, and the section of static particles acts as an insulating material as described, since it is neither flowable nor permeable.

[0016] The external casing can be fabricated using metalworking techniques.

[0017] The amount and thickness of stationary particles can be sized, in particular, depending on low thermal conductivity, the operating temperature of the device, and the temperature of the external environment.

[0018] In one embodiment, a particle-flowable bed is heated by an element immersed in the bed itself. In particular, such an element may be an electrical means, such as a resistor.

[0019] The heating means may be or include different types of heat exchange elements, or thermal energy associated with solar radiation focused by a suitable light system may be transferred to the particle bed.

[0020] The temperature within the internal region of a device in a fluidized floor can typically reach very high values, often exceeding 600°C.

[0021] As mentioned, the section of non-moving particles located outside the separation means made of a metal sheet, which is usually equal to about 0.3 W / (mK) and has a low equivalent thermal conductivity mainly depending on the vacuum degree in the particles, insulates the central region housing that accommodates the fluidized bed and enables it not to transfer thermal energy outward. The temperature of the outer casing of the device can then be slightly higher than room temperature.

[0022] The fluidizing air is sent from the bottom to the region of the movable bed, and this air remains confined by the separation means made of a metal sheet.

[0023] In particular, the separation means made of a metal sheet is connected to the bottom or the floor of the device, preferably welded thereon, which prevents the fluidizing air from escaping and thus makes it airtight against such air.

[0024] The separation means is made of a material resistant to the high temperature of the fluidized bed and preferably has a profile with cross-waves that allow its expansion in the horizontal direction. The expansion in the longitudinal direction, i.e., the vertical direction, can occur freely upward.

[0025] In a preferred configuration, the profile of the metal sheet is thus made wavy.

[0026] In a preferred configuration, the fluidizing means avoids the base or the bottom of the device by determining a fixed head of particles that overlaps under the fluidized bed of particles during operation. Such a fixed head is neither ventilated nor fluidized like the static section around the particles, which enables heat insulation towards the bottom of the device by further maintaining the connection with the separation means made of a sheet.

[0027] The present invention makes it possible to eliminate the functional problems found in known heat insulation systems that provide for the combined use of a refractory sheath and an insulating sheath.

[0028] Furthermore, in the embodiment, the present invention enables perfect airtightness of the fluidized air, and as a result, the correct operation of the fluidized bed of particles.

[0029] As a result, the device becomes more reliable and has high storage and heat exchange efficiency.

[0030] The proposed device stores thermal energy to flexibly generate, for example, electrical energy and / or thermal energy. This can constitute a doubling module for plants to generate electrical and thermal energy to provide to local communities and industrial plants.

[0031] Other advantages, features, and modes of use of the present invention will become apparent from the following detailed description of some embodiments, which are presented as examples rather than for limiting purposes.

[0032] The enclosed diagrams are shown below. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic plan view of a preferred embodiment of the thermal energy storage and release device according to the present invention. [Figure 2] This figure shows the front section of the device in Figure 1, executed according to line A-A in Figure 1. [Figure 3] This figure shows the lateral section of the device in Figure 1, executed along line B-B in Figure 1. [Figure 4A] Figure 1 is a schematic perspective view of a preferred embodiment of the corrugated metal sheet used in the device. [Figure 4B] This is a cross-sectional view of a preferred embodiment of the corrugated metal sheet used in the device shown in Figure 1. [Modes for carrying out the invention]

[0034] The sizes shown in the diagrams above are intended merely as examples and do not necessarily represent proportionality.

[0035] Various embodiments and variations of the present invention will be described hereafter with reference to the figures mentioned above.

[0036] Similar components are shown in different diagrams using the same numerical references.

[0037] In the following detailed description, additional examples and variations relating to the examples and variations already covered in the same description are illustrated only in terms of differences from those already shown.

[0038] Furthermore, the different embodiments and variations described below are likely to be used in combination, where appropriate.

[0039] Referring first to Figures 1 to 3, a thermal energy storage and exchange device according to a preferred embodiment of the present invention is shown overall at 100.

[0040] Device 100 comprises an airtight and solid particle-sealing external casing 1, which is advantageous to be fabricated using metalworking techniques.

[0041] In this example, the external casing 1 encloses and defines all internal components of the device. Advantageously, it has a square plane. As shown in Figures 2 and 3, the external casing may have an internal coating or coat 7 made of insulating material, for example, extending around the upper periphery of the device 100.

[0042] An internal partitioning means 3 is housed within the casing 1, particularly in the form of a skirt or wall extending along the closed perimeter. The partitioning means 3 defines an internal containment compartment or volume 40. In this example, the internal compartment 40 has a substantially rectangular parallelepiped shape.

[0043] In this example, the partitioning means 3 also has a quadrilateral plane that extends in accordance with the perimeter of the closed rectangle. Advantageously, the partitioning means is centrally located and is therefore spatially equidistant from the outer casing 1 in the plan view, as can be seen in Figure 1.

[0044] Between the external casing 1 and the internal partitioning means 3, the external containment compartment or volume section 20 is separated from and circumscribing the internal containment compartment 40. Therefore, in this example, the external compartment 20 has a substantially frame-like, particularly rectangular, shape in the plan view.

[0045] Within the internal containment compartment 40, a floor 4 into which fixed particles can flow is provided.

[0046] Such particles can be silica sand or other granular material that can withstand high temperatures, and preferably they have a regular shape, preferably spherical, and preferably a size of about 100 to 300 microns.

[0047] Within the external containment compartment 20, a stationary, i.e., non-fluidized floor 2 of solid particles is received. The particles of the stationary floor 2 can have the same properties as those of the fluidized floor 4.

[0048] The stationary particle bed 2 acts as a support surface for thermal insulation between the flowable particle bed 4 and the external casing 1, and thus the environment outside the device 100.

[0049] The device 100 also includes a fluidizing means 6 for a particle-fluidizable floor 4, which is actually configured to supply a fluidizing gas, particularly air, to the inside of the floor itself.

[0050] In this example, the fluidizing means 6 comprises a plurality of nozzles 60 for dispensing the fluidizing gas. Advantageously, these nozzles are arranged on the floor of the internal containment compartment 40, particularly in two or more parallel rows.

[0051] Advantageously, as can be seen in Figure 1, the nozzle 60 is positioned in the center of the floor 4, which is capable of particle flow, in the plan view.

[0052] The fluidizing means 6 can be configured to determine the differential fluidization of the floor 4, particularly in the central part of the floor, i.e., the part where the nozzle 60 is positioned in this example, where particles can flow at a higher particle velocity. Based on this modified form or other alternative implementations, the peripheral portion of the floor 4 adjacent to the partitioning means 3 is cooler and / or less dynamic than the central portion, thus suppressing potential thermal and / or mechanical wear of the partitioning means 3.

[0053] Furthermore, in a preferred embodiment, the fluidizing means 6 is configured to deliver a fluidizing gas at a predetermined height of the particle-fluidable bed 4 such that the lower heads 44 of the particles that are not fluidized remain.

[0054] In this way, insulation of the floor portion of device 100 facing the external environment is ensured, which is advantageous for the sustainability of the system. In Figure 2, the height of this head is illustrated and specified by reference to H.

[0055] The internal partitioning means 3 is made of a metal sheet and is configured to be airtight and particle-sealing by preventing the passage of fluidized gas and particles from the fluidizable floor 4 within the external containment compartment 20.

[0056] Referring also to Figures 4A and 4B, the internal partition means 3 is preferably made of a corrugated metal sheet.

[0057] For operating temperatures up to 700°C, the material constituting the sheet can be stainless steel, and for higher values, a nickel-based alloy can be used.

[0058] Preferably, the metal sheet has a thickness of about 1 mm or less.

[0059] In a preferred embodiment related to Figure 4, the corrugated metal sheet has a corrugated profile with a transverse direction, particularly a substantially sinusoidal curvature.

[0060] Preferably, the waveform profile has a wave pitch that falls within the range of approximately 100 to 200 mm.

[0061] Preferably, the waveform profile has a wave height h that falls within the range of approximately 10 to 40 mm.

[0062] Preferably, the waveform profile has a radius of curvature r that falls within the range of approximately 20 to 50 mm.

[0063] The device 100 further comprises means 5 for heating a flowable bed 4.

[0064] In this example, the heating means 5 is immersed in a fluid bed of particles 4 and / or is wrapped in such a manner that it releases thermal energy when fluidized by this bed of particles.

[0065] In a preferred embodiment, the heating means 5 comprises one or more bar-shaped electrical resistor means 50 inserted longitudinally, particularly within a bed 4 into which particles can flow.

[0066] One or more of the devices described above can be used in electrical or thermal energy generation plants, or in other types of industrial plants, such as desalination plants.

[0067] The present invention has been described herein with reference to preferred embodiments. It is intended that other embodiments belonging to the same inventive core may exist, as defined by the scope of protection of the claims reported herein.

Claims

1. A thermal energy storage and exchange device (100), Airtight external casing (1), An internal partitioning means (3) that divides the internal containment compartment (40), The external casing (1) is positioned externally in contact with the external partitioning means (3), thereby separating the external containment compartment (20) between the external casing and the partitioning means (3), and also externally in contact with the internal containment compartment (40), and the internal partitioning means A flowable floor (4) for solid particles received within the internal containment compartment (40), A stationary bed (2) of solid particles that is not fluidized and is received within the external containment compartment (20) and configured to act as an insulating means, The system comprises means (5) for heating the flowable bed (4), A thermal energy storage and exchange device in which the internal partitioning means (3) is made of a metal sheet and is configured to be airtight and particle-sealed by preventing the passage of fluidized gas and particles in the external containment compartment (20) through the fluidizable floor (4).

2. The device (100) according to claim 1, wherein the external casing (1) is made by metalworking.

3. The device (100) according to claim 1 or 2, comprising means (6) for fluidizing the fluidizable bed (4) of particles, configured to supply a fluidizing gas, particularly air, through the fluidizable bed (4) of particles.

4. The device (100) according to claim 3, wherein the fluidizing means (6) comprises a plurality of nozzles (60) for dispensing fluidizing gas.

5. The device (100) according to claim 4, wherein the discharge nozzle (60) is located on the floor of the internal containment compartment (40).

6. The device (100) according to claim 3 or 4, wherein the discharge nozzles (60) are arranged in two or more parallel rows.

7. The device (100) according to any one of claims 3 to 5, wherein the discharge nozzle (60) is located in the center of the flowable bed (4) of particles in a plan view.

8. The device (100) according to any one of claims 2 to 6, wherein the fluidizing means (6) is configured to determine the differential fluidization of the fluidizable bed (4) of particles at a higher particle velocity, particularly in the central part of the fluidizable bed (4) of particles.

9. The device (100) according to any one of claims 2 to 7, wherein the fluidizing means (6) is configured to deliver a fluidizing gas to a predetermined height (H) of the fluidizable bed (4) of particles such that the lower heads (44) of the particles that are not fluidized remain.

10. The device (100) according to any one of claims 1 to 9, having a head (44) of non-fluidizable particles positioned below the fluidizable bed (4) of particles.

11. The device (100) according to any one of claims 1 to 10, wherein the internal partitioning means (3) is positioned centrally with respect to the external casing (1).

12. The device (100) according to any one of claims 1 to 11, wherein both the external casing (1) and the internal partitioning means (3) have a rectangular shape in a plan view.

13. The device (100) according to any one of claims 1 to 12, wherein the internal partitioning means (3) has a profile having a curved portion to allow transverse expansion.

14. The device (100) according to any one of claims 1 to 13, wherein the internal partitioning means (3) is made of a corrugated profile metal sheet.

15. The device (100) according to claim 12 or 13, wherein the profile is substantially sinusoidal.

16. The device (100) according to claim 15, wherein the profile has a wave pitch (l) that falls within the range of approximately 100 to 200 mm.

17. The device (100) according to claim 14 or 15, wherein the profile has a wave height (h) that falls within the range of approximately 10 to 40 mm.

18. The device (100) according to any one of claims 1 to 17, wherein the internal partitioning means (3) is made of a metal sheet having a thickness of about 1 mm or less.

19. The device (100) according to any one of claims 1 to 18, wherein the internal partitioning means (3) is made of a stainless steel metal sheet or a nickel-based alloy.

20. The device (100) according to any one of claims 1 to 19, wherein the heating means (5) is immersed in the fluid bed (4) of particles and is wrapped in such a manner that it releases thermal energy when e / o fluidized by the fluid bed of particles.

21. The device (100) according to any one of claims 1 to 20, wherein the heating means (5) comprises, in particular, one or more bar-shaped electrical resistor means (50) inserted longitudinally into the flowable bed (4) of particles.

22. An electric or thermal energy generation plant comprising one or more devices (100) as described in any one of claims 1 to 21.

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