WO2023089220A1

WO2023089220A1 - A thermal energy storage tank floor

Info

Publication number: WO2023089220A1
Application number: PCT/ES2022/070746
Authority: WO
Inventors: Kurt Friedrich DREWES; Bruce Alexander Leslie; Sergio DAVILA BORRAZ; David CUBEL RECASENS
Original assignee: Vast Solar Pty Ltd; Contratos Y Diseños Industriales S.A.
Priority date: 2021-11-18
Filing date: 2022-11-18
Publication date: 2023-05-25

Abstract

The present invention relates to a thermal energy storage tank floor that comprises a substantially circular central floor plate, an annular floor plate and an annular inner expansion joint. The annular floor plate is arranged concentrically with the central floor plate in such a way that the two floor plates form a pair of radially adjacent floor plates. The annular inner expansion joint connects said radially adjacent floor plates and is configured to offset, at least partially, the thermal expansion of the central floor plate and/or of the inner floor plate.

Description

A thermal energy storage tank floor Technical field

The present disclosure is directed to a thermal energy storage tank floor, a thermal energy storage tank base and a thermal energy storage tank.

Background

Thermal energy storage tanks are known for storing thermal energy, such as molten salts, generated by concentrating solar thermal power (CSP) plants. These cylindrical storage tanks are typically large in diameter (35-50m) and configured to hold thousands of tons of molten solar salt (30,000 tons or more) at elevated temperatures up to 600°C (and occasionally exceeding it).

These storage tanks are typically constructed by welding together stainless steel plates to form the floor, side wall, and roof of the storage tanks. A plurality of steel plates are arranged on a suitable, thermally insulated and reinforced foundation and welded together to form the floor of the storage tank, and a plurality of steel plates are welded together to form the side wall of the tank storage. The side wall is typically connected to the floor by welding the lowermost edge of the side wall perpendicular to the floor.

Storage tanks of this type are subjected to significant thermal stress with changes in temperature and volume of molten salt. Heating the tank and adding heated molten salt to the empty storage tank will cause the steel plates to expand radially outward. Typically, once charged with molten salt, tanks are maintained with at least a small amount of molten salt at the desired temperature to keep the tank floor expanded. However, small increases and decreases in the temperature of the molten salt will cause the soil to expand and contract respectively. Similarly, cyclical variations in the depth of the molten salt in the tank will vary the hydrostatic pressure in the tank at ground level, and this will cause hoop stresses with the walls expanding and contracting as the depth of the molten salt increases. increases and decreases, respectively.

The ability of the tank floor to radially expand and retract is impeded by friction between the floor and the foundation and the vertical pressure on the foundation due to gravity acting on the tank and its contents. The frictional constraint is especially important at the corner of the tank, where the weight of the tank walls provides a substantial and constant vertical load from the foot of the wall on the foundation. When the weight of the tank on the toe of the wall and the frictional conditions between the toe and the foundation do not allow the toe of the wall to move radially in response to thermal expansion and contraction of the floor plates, the buckling of the floor plates, causing the rupture and failure of the tank. It should be noted that this has been overcome to some extent by using a suitable foundation matrix of refractory material, as well as a dry lubricant between the tank floor and the foundation to reduce frictional forces.

Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant and/or combined with other pieces of prior art by a person skilled in the art.

Compendium

In a first aspect of the present invention there is provided a thermal energy storage tank floor comprising: a substantially circular central floor plate; an annular floor plate arranged concentrically with the central floor plate such that the two floor plates form a pair of radially adjacent floor plates; and an annular expansion joint joining said radially adjacent floor plates, and wherein the expansion joint is configured to at least partially compensate for thermal expansion of the central floor plate and/or the annular floor plate.

In one embodiment, the inner expansion joint may comprise a bellows ring having an inner circumferential edge welded to an outer circumferential part of the central floor plate, and an outer circumferential edge welded to an inner circumferential part of the floor plate. inner ring.

In one embodiment, the bellows ring may have an omega-shaped profile.

The bellows ring may have a central circular profile with a bottom opening, terminating in uprights welded to adjacent floor plates.

The central part may be formed of an annular tube section with a bottom cut to define an opening spanning a gap between adjacent floor plates.

The bellows ring can describe a central convex part that is fused with concave support parts welded to adjacent floor plates. The central convex part and the concave support parts may comprise continuous circular arcs, which may share the same radius.

A tangential extension of a first end of a first circular arc may define the inner circumferential edge of the inner expansion joint; a tangential extension of a first end of a second circular arc may define the outer circumferential edge of the inner expansion joint; and a third circular arc may connect a second end of the first circular arc with a second end of the second circular arc.

An arc angle of the first and second circular arcs may be approximately half of an arc angle of the third circular arc.

In one embodiment, the bellows ring may have a figure-of-eight profile.

The bellows ring may be formed of upper and lower pipe sections, the upper pipe section having a lower opening and the lower pipe section having upper and lower openings, the upper opening of the lower pipe section being attached to and communicating with the lower opening of the upper pipe section and terminating the lower opening of the lower pipe section at uprights welded to adjacent floor plates.

The radially adjacent floor plates can be arranged such that an annular clearance is formed between their opposite outer and inner circumferential edges, the annular clearance being traversed by the annular expansion gap.

In one embodiment, the expansion joint may further comprise a contraction stroke limiter configured to limit the relative movement of radially adjacent floor plates away from each other due to thermal contraction.

The contraction stroke limiter may comprise a series of tie rods.

Each brace may include: i. a first shell attached to one of the radially adjacent floor plates joined by the expansion joint, the first shell defining a first hole having an axis extending in a radial direction of the tank floor; ii. a second bushing fixed to the other radially adjacent floor plate joined by the expansion joint, the second bushing defining a second hole coaxial with the first hole of the first bushing; and iii. a restrictor pin extending through the first and second holes of the first and second bushings, respectively, and iv. wherein the restrictor pin is plugged at each end with a head portion having a diameter larger than a diameter of the first and second holes, respectively. In one embodiment, the contraction stroke limiter may comprise a series of interconnecting formations extending from adjacent floor plates, the interconnecting formations comprising a series of head and neck formations alternating with head and head receiving recesses. neck, where the head and neck formations extending from one floor plate are held captive within the corresponding receiving head and neck formations of the other adjacent floor plate, and vice versa, whereby the floor plates Adjacent ones are capable of limiting radial movement within the corresponding recesses.

Interconnecting formations can be integrally formed into adjacent floor plates, preferably by laser cutting.

In another embodiment, a tangential extension of a first end of a first circular arc may define the inner circumferential edge of the inner expansion joint; a tangential extension of a first end of a second circular arc may define the outer circumferential edge of the inner expansion joint; and a third circular arc may connect a second end of the first circular arc with a second end of the second circular arc. The cross section of the expansion joint may have a line of symmetry passing through a center of the third circular arc, and an arc angle of the first and second circular arcs may be approximately half an arc angle of the third circular arc.

In another embodiment, the radially adjacent floor plates can be arranged so that an annular clearance is formed between their opposite outer and inner circumferential edges.

In one embodiment, the tank floor may further comprise: at least one additional annular floor plate arranged concentrically with the central and annular floor plates; and at least one corresponding additional annular expansion joint joining the outer and inner circumferential portions of the radially adjacent annular floor plates, and wherein the at least one additional expansion joint is configured to at least partially compensate for thermal expansion of at least one additional expansion joint. least one of the radially adjacent annular floor plates.

The at least one additional expansion joint may comprise a bellows ring having inner and outer circumferential edges welded to inner and outer circumferential portions, respectively, of radially adjacent annular floor plates.

In another embodiment, all expansion joints may have the same stress-strain curve. In an alternate embodiment, the at least one expansion joint may have a different stress-strain curve than the at least one other expansion joint. In this alternative embodiment, each radially successive expansion joint may have a curve of increasingly pronounced stress-strain, so that the internal expansion joint exhibits the greatest degree of strain in response to the same stress input. In another embodiment, all of the annular floor plates have the same radial width. In an alternative embodiment, the at least one annular floor plate may have a different radial width from the radial width of the at least one other annular floor plate. In this alternative embodiment, each successive radially annular floor plate has a radial width that is less than a radial width of its preceding radially annular floor plate, such that the inner annular floor plate has the greatest radial width.

In a second aspect of the present invention there is provided a thermal energy storage tank base comprising: a foundation; and a thermal energy storage tank floor according to the first aspect, the foundation supported tank floor.

In a third aspect of the present invention there is provided a thermal energy storage tank comprising: a thermal energy storage tank base according to the second aspect; a cylindrical side wall extending from the tank floor; and a roof supported on the side wall.

As used herein, except where the context otherwise requires, the term "comprising" and variations of the term, such as "comprising", "comprising", and "comprising", are not intended to exclude other additives, components, integers or stages.

Other aspects of the present invention and other embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

Figure 1 is an isometric view of a thermal energy storage tank floor in accordance with the present disclosure.

Figure 2 is a sectional isometric view of the tank floor of Figure 1 .

Figure 3 is an enlarged cross-sectional view of a first embodiment of the expansion joint and radially adjacent floor plates of the tank floor area identified "A" in Figure 2.

Figure 4 is an enlarged cross-sectional view of a second embodiment of an expansion joint in accordance with the present disclosure.

Figure 5 is an enlarged cross-sectional view of a third embodiment of an expansion joint according to the present disclosure. Figures 6a and 6b show detailed plan views of second embodiments of floor plate retaining means in the retracted and extended positions.

Figure 7 is a sectional isometric view of a thermal energy storage tank base according to the present disclosure.

Figure 8 is a sectional isometric view of a thermal energy storage tank according to the present disclosure.

Figure 9 is a sectional isometric view of another thermal energy storage tank floor in accordance with the present disclosure.

Figure 10 is a sectional isometric view of another thermal energy storage tank floor according to the present disclosure.

Detailed description of embodiments

Figures 1 and 2 are isometric and isometric sectional views, respectively, of a thermal energy storage tank floor 100 in accordance with the present disclosure, together with an inner section of a cylindrical side wall 200 extending from the floor 100. As As shown in Figure 8, when supported by a foundation 300 to form a tank base 400 (see also Figure 7), the tank floor 100 can be combined with a side wall 200 and a roof 500 to form a storage tank. thermal energy storage 600 for storing thermal energy. The thermal energy stored in the thermal energy storage tank 600 may be in the form of molten salt generated from a concentrating solar thermal power plant. However, it is also envisioned that other forms of thermal energy can be stored in the storage tank 600.

The tank floor 100 comprises a substantially circular central floor plate 110, seven annular floor plates 120a-g arranged concentrically with the central floor plate, and seven corresponding annular expansion joints 130a-g. The seven annular floor plates 120a-g comprise an inner annular floor plate 120a radially adjacent to the central floor plate 1 10, and six outer annular floor plates 120b-g arranged radially in succession from the inner annular floor plate. 120a. The seven annular expansion joints 130a-g comprise an inner expansion joint 130a joining radially adjacent central and inner annular floor plates 1 10, 120a, and six outer expansion joints 130b-g, each joining a pair of radially adjacent annular floor plates 120a-g.

Each expansion joint 130a-g is configured to compensate, at least partially, for the thermal expansion of at least one of the floor plates in the pair of floor plates. radially adjacent that unites. Consequently, the internal expansion joint 130a is configured to compensate, at least partially, for the thermal expansion of the central floor plate 110 and/or the internal annular floor plate 120a. Similarly, each of the six outer expansion joints 130b-g is configured to at least partially compensate for the thermal expansion of at least one of the annular floor plates 120a-g of said pair of annular floor plates 120a-g. radially adjacent joined by the respective expansion joint 130b-g.

To at least partially compensate for thermal expansion, the expansion joints 130a-g are configured in such a way as to allow a certain degree of relative movement between the pair of joined radially adjacent floor plates 1 10, 120a-g. Consequently, when one floor plate of the joined pair expands under thermal stress, the respective expansion joint absorbs at least a part of this thermally induced deformation before it is transmitted to the radially adjacent floor plate as compressive stress in the tank floor plan 100.

The specific configuration of the expansion joint may depend on the characteristics of the respective storage tank. In some embodiments, a bellows-type expansion joint may be used in conjunction with an annular clearance formed between opposite circumferential edges of radially adjacent floor plates. In other embodiments, a bellows-type expansion joint may be used in conjunction with a sliding lap that occurs between the circumferential edges of radially adjacent floor plates. In other embodiments, the sliding overlap between the circumferential edges of radially adjacent floor plates may itself form the expansion joint. When a sliding overlap is used, it will be appreciated that the expansion joint may comprise separate or additional features that limit the relative sliding stroke.

A specific example of an expansion joint according to one embodiment of the present disclosure will now be described in more detail with reference to the cross section of the inner expansion joint 130a shown in Fig. 3.

The inner expansion joint 130a is a bellows-type expansion joint comprising a bellows ring 140a having an inner circumferential edge 142a welded to an outer circumferential part of the central floor plate 110, and an outer circumferential edge 144a welded to an inner circumferential portion of the inner annular floor plate 120a. In this embodiment, the inner and outer circumferential edges 142a, 144a are welded at an angle to the respective parts of the central and inner annular floor plates 110, 120a. It will be appreciated that, in embodiments using other configurations, the edges Inner and outer circumferential edges 142a, 144a may be butt welded to respective circumferential edges of radially adjacent floor plates.

Bellows ring 140a describes a modified "Q" (omega) in cross section. More specifically, the cross section of the bellows ring 140a is defined by three continuous circular arcs bounded by a pair of tangential extensions. A tangential extension 141 a of a first end of a first circular arc 146a runs parallel to the plane of the tank floor 100 and overlaps a part of the central floor plate 110 to define the internal circumferential edge 142a of the internal expansion joint. 130a. A tangential extension 143a of a first end of a second circular arc 147a also runs parallel to the plane of the tank floor 100 and overlaps a portion of the inner annular floor plate 120a to define the outer circumferential edge of the inner expansion joint. 130a. A third circular arc 148a connects a second end of the first circular arc 146a with a second end of the second circular arc 147a.

In this embodiment, the three continuous circular arcs 146a, 147a, 148a share the same radius, and the cross section of the expansion joint 130a has a line of symmetry passing through a center of the third circular arc 148a. Consequently, an arc angle of the first and second circular arcs 146a, 147a is approximately half of an arc angle of the third circular arc 148a. Such a configuration may allow the expansion joint 130a to distribute the applied stress relatively evenly over the entire cross section of the bellows ring 140a. In this embodiment, an arc angle of the first and second circular arcs 146a, 147a is approximately 135°, and an arc angle of the third circular arc 148a is approximately 270°. It will be appreciated that, in embodiments where it may be desirable to concentrate stress at certain points in the cross section of the bellows ring, one or more of these characteristics may be varied to achieve the desired result.

The bellows ring 140a can be made by cutting the three circular arcs 146a, 147a, 148a from tubes of the same radius, and then welding them with flat plates that form the tangential extensions 141a, 143a. Alternatively, the cross section of the bellows ring 140a can be rolled from a length of flat plate, which is subsequently (or simultaneously) rolled into a circular arc forming a section of the bellows ring 140a.

The central and inner annular floor plates 110, 120a are arranged in such a way that an annular gap 150 is formed between their opposite outer and inner circumferential edges. The radial width of this annular gap 150 defines the maximum relative movement of these two floor plates 1 10, 120a radially adjacent to each other when they undergo thermal expansion. The expansion joint 130a further comprises a separate contraction stroke limiter 160 configured to limit the relative movement of the radially adjacent central and inner annular floor plates 1 10, 120a away from each other due to thermal contraction. It will be appreciated that, in other embodiments, the bellows ring 140a itself may be configured to act as a contraction stroke limiter.

In this embodiment, the contraction stroke limiter 160 comprises first and second bushings 162, 164 attached to the outer and inner circumferential portions of the central and inner annular floor plates 1 10, 120a, respectively. The first bushing 162 defines a first hole (not shown) having an axis extending in a radial direction of the tank floor 100. The second bushing 164 defines a second hole (also not shown) coaxial with the first hole of the first bushing 162 .

The contraction stroke limiter 160 further comprises a restrictor pin 166 which extends through the first and second holes of the first and second bushings 162, 164, respectively. The restraint pin 166 is covered at each end with a head portion having a diameter greater than a diameter of the first and second holes, respectively. Consequently, the distance between the head portion defines the maximum relative movement of the two radially adjacent floor plates 1 10, 120a away from each other when subjected to thermal contraction.

In this embodiment, the tank floor 100 comprises seven annular plates 120a-g which together with the central plate 110 form seven annular clearances traversed by seven annular expansion joints 130a-g. It will be appreciated that, in other embodiments, the number of annular plates and corresponding expansion joints may differ depending on a number of tank characteristics, such as tank size, temperatures to which the floor is expected to be exposed, temperature variations in the soil, thickness, width and material of the annular plates, etc. For example, smaller tanks may require only one ring plate or one or two ring plates, while larger tanks may require more than seven ring plates.

In the tank floor 100 of this embodiment, all expansion joints 130a-g are substantially identical, that is, they all comprise substantially identical bellows rings made of the same material and having the same cross-sectional shape, height, width and wall thickness, and all are constrained by the same expansion/contraction stroke limitations. Consequently, they all have the same stress-strain curve, that is, they exhibit the same degree of strain in response to the same stress input.

It will be appreciated that, in other embodiments, it may be desirable to configure the expansion joints 130a-g such that at least one expansion joint has a curve of stress-strain different from the other expansion joints. It may also be desirable to configure the expansion joints 130a-g such that at least one expansion joint has a different expansion and/or contraction stroke limit from the remaining joints.

For example, for a storage tank that stores thermal energy in the form of molten salt of uniform temperature, it is understood that the stress applied to the expansion joints 130a-g increases for each radially successive expansion joint, that is, the expansion joint radially outermost expansion 130g is exposed to the greatest stress and the inner expansion joint 130a is exposed to the least stress. Accordingly, it may be desirable to configure the expansion joints 130a-g such that at least the inner expansion joint 130a exhibits a greater degree of deformation than one or more of the remaining expansion joints 130b-g in response to the same input. of effort. In some embodiments, it may be desirable to configure each radially successive expansion joint 130a-g to have an increasingly steeper stress-strain curve such that the inner expansion joint 130a exhibits the greatest degree of strain in response to pressure. same effort input. It will be understood that this can be accomplished by varying one or more of the defining characteristics of expansion joints 130a-g, such as type, cross-sectional shape, height, width, wall thickness, etc.

In the tank floor 100 of this embodiment, all of the annular floor plates 120a-f, apart from the radially outermost annular floor plate 120g, have substantially the same radial width. Consequently, for a storage tank that stores thermal energy in the form of molten salt of uniform temperature, each of these annular floor plates 120a-f has the same increase in width that occurs due to thermal expansion and that the joints of dilation 130a-g must partially compensate. It will be appreciated that, in other embodiments, it may be desirable to provide at least one annular floor plate with a radial width that is different from the radial width of at least one other annular floor plate. In some embodiments, it may be desirable to provide each successive radially annular floor plate with a radial width that is less than a radial width of its preceding radially annular floor plate such that the inner annular floor plate has the greatest radial width. Configuring the tank floor 100 in this manner can allow each successive radially expansion joint to partially compensate for a lesser amount of thermal expansion than the expansion joint radially preceding it.

Referring now to Figure 4, an enlarged cross-sectional view of a second embodiment of an omega (Q)-shaped expansion joint 402 includes an annular tube section 404 having a short arcuate portion cut from its base, the open end faces 408 of the tube section being angle welded to supports annular uprights 410. These supports are in turn welded at 412 to the upper end faces of the adjacent floor plates 120a and 120b. In this particular embodiment, the pipe section has a diameter of 136.5 mm and a thickness of 4 2 mm, and the base plates are 8 mm thick. This allows the pipe section to flex in response to expansion of the floor plates relative to each other and contraction relative to each other as a result of thermal variations. It will be appreciated that the dimensions of the pipe, supports and floor plates can vary significantly depending on numerous factors, such as tank size, anticipated temperature variations and expansion joint spacing.

Figure 5 shows an enlarged cross-sectional view of a third embodiment of a figure-of-eight expansion joint 501 having a lower part formed by two annular tube halves 502 and 504 joined at their lower ends to the upper end faces of adjacent floor plates 120a and 120b in the same manner as tube section 404 by means of annular uprights 510 and fillet welds 511. An upper annular tube section 512 has the lower ends 514 welded to the upper ends 516 of the halves of lower tubes through connection strips 518. The resulting expansion joint has a greater bending capacity than that of the second embodiment and, therefore, is capable of bridging a greater gap between adjacent floor plates to allow greater degrees of expansion and contraction when necessary.

The expansion joints 402 and 501 may further comprise a separate contraction stroke limiter, configured to limit the relative movement of radially adjacent floor plates to one another due to thermal contraction. This may take the form of a tie rod of the type illustrated in Figure 3 which extends between uprights 510. Alternatively, as shown in Figures 6a and 6b, adjacent floor plates 120a and 120b are laser cut with profiles of "lollipop" that interconnect. Floor plate 120a has a series of bulbous head portions 121 extending from respective notched neck portions 123 and alternating with head receiving recesses 125. Floor plate 120b has shaped head portions 127 identical and notched neck parts 129 that alternate with recesses to receive the head 131 . It is evident how the head parts 121 of the floor plate 120a move and are held captive within the recesses 131 of the floor plate 120b and the head parts 127 of the floor plate 120b move and are held captive within of the corresponding recesses 125 in the floor plate 120a between the retracted and extended positions indicated in Figures 6a and 6b respectively. In the extended position of Figure 6b, further outward movement is limited by the heads 121 abutting the shoulders 121 a of the tapered openings defined by the opposing heads 127, and vice versa. The contraction stroke limiting arrangement of Figures 6a and 6b can be laser cut from larger floor plates so that they are integral with adjacent floor plates. Alternatively, they can be laser cut from annular strips which are welded in place to the upper end faces of adjacent floor plates. The expansion joints are then welded to the continuous landing regions indicated in dashed outline at 133 and 135 of the adjacent floor plates 120a and 120b.

It will be appreciated that this form of contraction stroke limiter can be applied to any of the types of expansion joints described in the specification.

From the above description, it will be understood that the use of at least one annular expansion joint at least partially isolates a central part of the tank floor 100 from a circumferential part of the tank floor 100, so that thermal expansion of a party is not transmitted, or only partially, to the other party. This structure allows the gradient of the overall thermal stress curve of the tank floor 100 to be reduced further than is possible by merely varying the material and dimensions of the tank floor 100. Accordingly, it will be appreciated that the number, type, The characteristics (stress-strain curve) and radial interval of expansion joints can be varied to achieve the desired overall thermal stress-strain curve of the tank floor 100 and reduce the likelihood of buckling occurring in the tank floor. tank 100. The type of expansion joint can also vary based on the degree of expansion and contraction required for a particular tank or location within the tank. For example, omega type expansion joints can be used in conjunction with figure eight type expansion joints.

A thermal energy storage tank foundation 400 will now be described with reference to Fig. 7. The tank foundation 400 comprises a foundation 300 and the thermal energy storage tank floor 100 described above, with the tank floor 100 supported on foundation 300. Foundation 300 is prepared from a properly insulated and thermally strengthened matrix of refractory material. In some embodiments, a dry lubricant is also applied to the top surface of the foundation 300.

In some embodiments, the central floor plate 110 and all the annular floor plates 120a-g are arranged on the upper surface of the foundation 300, before being joined by the respective expansion joints 130a-g. In other embodiments, the central floor plate 110 and the inner annular floor plate 120a are first arranged on the upper surface of the foundation 300 before being joined by the inner expansion joint 130a. Each outer annular floor plate 120b-g is then arranged on the upper surface of the foundation 300 and is joined to its preceding radially annular plate with the respective expansion joint. exterior 130b-g, before its successive radially annular floor plate 120c-g is arranged on the foundation 300.

In another embodiment, the entire tank floor is fabricated from a series of adjoining floor plates that are welded together in any suitable pattern, including, for example, segments. The annular floor plates are then defined by laser cutting them in the manner illustrated in Figures 6a and 6b, using a series of concentric circular cuts with interconnected head and neck portions or "lollipop" profiles.

In Fig. 8 there is shown a thermal energy storage tank 600 comprising the thermal energy storage tank base 400 described above. A plurality of wall plates (not shown) are welded together to form the cylindrical side wall 200 that extends from the tank base 100. A plurality of roof plates (not shown) are welded together to form the roof 500 that it has a peripheral edge supported and welded to the upper edge of the cylindrical side wall 200. Since the thermal energy storage tank 600 is intended to store a thermal energy storage medium (for example, molten salt), the floor 100, including expansion joints 130a-g, wall 200 and roof 500 must be made of a suitable alloy steel material capable of withstanding high temperatures and masses. Suitable materials include, but are not limited to, 316 stainless steel, A588 carbon steel, and Inconel.

As discussed above, the number, type, characteristics (stress-strain curve) and radial interval of annular expansion joints can be varied to achieve the desired overall thermal stress-strain curve of a tank floor and reduce the likelihood of buckling of the tank floor. For example, increasing the annular spacing between adjacent floor plates in the tank floor and the size of expansion joints connecting adjacent floor plates can increase the ability of expansion joints to compensate for thermal stresses applied to the tank. tank floor. However, the configuration of the expansion joints 130a-g, 402, 501 described above may restrict the size of the annular gap between adjacent floor plates. To overcome this restriction, the size of the expansion joints and annular gaps can be increased using the tank floor embodiment illustrated in Figure 9.

Figure 9 is a partial view of a tank floor 700 according to another embodiment, together with a lower section of a cylindrical wall 200 extending from the tank floor 700. The tank floor 700 is similar to the tank floor 100 in comprising a substantially circular central floor plate 710, a plurality of annular floor plates 720a-e arranged concentrically with the central floor plate 710, and a plurality corresponding set of annular expansion joints 730a-e each spanning an annular gap between radially adjacent floor plates. Accordingly, it will be understood that the general manner in which annular expansion joints 730a-e and annular gaps cooperate to compensate for thermal expansion of radially adjacent floor plates 710, 720a-e is the same as described above with with respect to the annular expansion joints 130a-g, 402, 501 and their corresponding annular gaps.

Similar to the annular expansion joint 130a described above, the annular expansion joints 730a-e are bellows-type expansion joints comprising a bellows ring having an inner circumferential edge welded to an outer circumferential portion of the bearing plate. radially inner adjacent floor, and an outer circumferential edge welded to an inner circumferential portion of the radially outer adjacent annular floor plate. However, the bellows ring of the annular expansion joints 730a-e differs from the bellows ring 140a described above in that they describe a semicircle in cross section.

Furthermore, while the annular floor plates 120a-g of the tank floor 100 shown in Figure 1 have a radial width that is substantially greater than the annular expansion joints 130a-g and their corresponding annular gaps (see, for example, 150 in Figure 2), the radial width of the annular floor plates 720a-e is actually less (or at least not greater) than the annular expansion joints 730a-e and their corresponding annular tank floor voids 700. Therefore For example, the semicircular cross section of the annular expansion joints 730a-e may have a radius of between 0.5 and 1 m and the annular floor plates may have a radial width of between 1 and 2 m. Without being limited by theory, such a size relationship between the annular expansion joints 730a-e (and corresponding annular gaps) and the floor plates 720a-e can provide greater compensation when the tank floor undergoes thermal expansion, and can obviate the need for a stroke limiter for when the tank floor undergoes thermal contraction.

However, it will be appreciated that difficulties may arise with the manufacture of such a size bellows ring using the similar method to that described above with respect to bellows ring 140a, for example, by rolling straight lengths of half-tube section into arc lengths. circular, and then welding them on the bellows ring. Accordingly, instead of attempting to form each bellows ring of annular expansion joints 130a-g as a smooth, circular ring, a plurality of straight half-tube sections 732 are used to approximate a circular ring. Each half-tube section 732 has an inner longitudinal edge 733, an outer longitudinal edge 734, a first axial edge 735, and a second axial edge 736. For each expansion joint 730a-e, the first axial edge 735 of a half-pipe section 732 is connected (eg, by butt welding) to the second axial edge 736 of an adjacent half-pipe section 732. In addition, for each expansion joint 730a-e, the inner longitudinal edge 733 of each half-pipe section 732 is connected (eg, by fillet welding) to a radially inner adjacent floor plate of the tank floor 700 and the edge outer longitudinal 734 of each half-pipe section 732 is connected (eg, by fillet welding) to an adjacent radially outer floor plate of tank floor 700. For example, for expansion joint 730a, inner longitudinal edge 733 of each half-pipe section 732 is connected to an outer circumferential portion of the central floor plate 710 and the outer longitudinal edge 734 of each half-pipe section is connected to an inner circumferential portion of the annular floor plate 720a. For each expansion joint 730b-e, the inner longitudinal edge 733 of each half-pipe section 732 is connected to an outer circumferential portion of a radially inner annular floor plate 720a-d and the outer longitudinal edge 734 of each half-pipe section. it is connected to an inner circumferential portion of a radially outer floor plate 720b-e.

Figure 10 is a partial view of a tank base 800 according to another embodiment. The tank base 800 comprises the tank floor 700 arranged on a substantially circular base plate 860. In this embodiment, the tank floor 700 is not connected to the base plate 860. This allows the tank floor 700 to expand and contract independently of the base plate 860. This can reduce the forces in the tank floor 700 as which expands and contracts, since the friction between the tank floor 700 and the base plate 860 can be less than the friction between the tank floor 700 and a base on which the tank floor 700 is placed. This can further reduce the possibility of the 700 tank floor buckling as it expands and contracts.

Base plate 860 may be formed by a plurality of plates welded together. The plates that form the base plate 860 may be formed of the same material as the plates that form the tank floor 700.

It will be appreciated that the tank floor 100 of the tank 600 illustrated in Figure 8 may be replaced by the tank floor 700 or the tank base 800.

Although tank floor 700 has been described and illustrated as having five annular floor plates 720a-e and five annular expansion joints 730a-e, it will be appreciated that tank floor 700 may have more or less annular floor plates and expansion joints. annular expansion depending on the size and operating parameters of the required storage tank. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or apparent in the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

CLAIMS A thermal energy storage tank floor comprising: a substantially circular central floor plate; an annular floor plate arranged concentrically with the central floor plate such that the two floor plates form a pair of radially adjacent floor plates; and an annular expansion joint joining said radially adjacent floor plates, and wherein the expansion joint is configured to compensate, at least partially, for thermal expansion of the central floor plate and/or annular floor plate. A thermal energy storage tank floor according to claim 1, wherein the expansion joint comprises a bellows ring having an internal circumferential edge welded to an external circumferential part of the central floor plate, and an external circumferential edge welded to an inner circumferential portion of the annular floor plate. A thermal energy storage tank floor according to claim 2, wherein the bellows ring has an omega-shaped profile. A thermal energy storage tank floor according to claim 3, wherein the bellows ring has a central part with a circular profile having a bottom opening, terminating in uprights welded to adjacent floor plates. A thermal energy storage tank according to claim 4 wherein the central part is formed of an annular tube section with a lower part cut to define an opening spanning a gap between adjacent floor plates. A thermal energy storage tank floor according to claim 3, wherein the profile describes a central convex part that merges with concave support parts welded to adjacent floor plates. A thermal energy storage tank according to claim 6, wherein the central convex part and the concave support parts comprise continuous circular arcs. A thermal energy storage tank floor according to claim 7, wherein: a tangential extension of a first end of a first circular arc defines the inner circumferential edge of the inner expansion joint; a tangential extension of a first end of a second circular arc defines the outer circumferential edge of the inner expansion joint; and a third circular arc connects a second end of the first circular arc with a second end of the second circular arc.

A thermal energy storage tank floor according to claim 8, wherein an arc angle of the first and second circular arcs is approximately half of an arc angle of the third circular arc.

A thermal energy storage tank floor according to claim 2, wherein the bellows ring has a figure-of-eight profile.

A thermal energy storage tank floor according to claim 10, wherein the bellows ring is formed of upper and lower pipe sections, the upper pipe section having a lower opening and the lower pipe section having upper and lower openings. bottom, the upper opening of the lower pipe section being attached to and communicating with the lower opening of the upper pipe section and the lower opening of the lower pipe section terminating in uprights welded to adjacent floor plates.

A thermal energy storage tank floor according to any one of the preceding claims, wherein the radially adjacent floor plates are arranged in such a way that an annular clearance is formed between their opposite outer and inner circumferential edges, the clearance being ring crossed by the annular expansion joint.

A thermal energy storage tank floor according to any one of the preceding claims, wherein the expansion joint further comprises a contraction stroke limiter configured to limit the relative movement of radially adjacent floor plates away from each other due to to thermal contraction.

A thermal energy storage tank floor according to claim 13, wherein the contraction stroke limiter comprises a series of tie rods.

A thermal energy storage tank floor according to claim 14, wherein each stay includes: a first bushing fixed to one of the radially adjacent floor plates joined by the expansion joint, the first bushing defining a first hole that it has an axis extending in a radial direction from the tank floor; a second bushing fixed to the other radially adjacent floor plate joined by the expansion joint, the second bushing defining a second hole coaxial with the first hole of the first bushing; and a restrictor pin extending through the first and second holes of the first and second bushings, respectively, and wherein the restrictor pin is plugged at each end with a head portion having a diameter larger than a diameter of the first and second holes, respectively.

A thermal energy storage tank floor according to claim 13, wherein the contraction stroke limiter comprises a series of interconnecting formations extending from adjacent floor plates, the interconnecting formations comprising a series of interlocking formations. alternating head and neck with head and neck receiving recesses, in which head and neck formations extending from one floor plate are held captive within corresponding head and neck receiving formations of the other floor plate adjacent, and vice versa, whereby adjacent floor plates are capable of limiting radial movement within the corresponding recesses.

A thermal energy storage tank floor according to claim 16, wherein the interconnecting formations are integrally formed into adjacent floor plates, preferably by laser cutting.

A thermal energy storage tank floor according to any one of the preceding claims, the tank floor further comprising: at least one further annular floor plate arranged concentrically with the central and annular floor plates; and at least one corresponding additional annular expansion joint that joins the outer and inner circumferential portions of the radially adjacent annular floor plates, and wherein the at least one additional expansion joint is configured to compensate, at least partially, for thermal expansion. of at least one of the radially adjacent annular floor plates.

A thermal energy storage tank floor according to claim 18, wherein the radially adjacent annular floor plates are arranged such that an annular gap is formed between their opposite outer and inner circumferential edges, the annular gap being crossed by the at least one additional corresponding annular expansion gap, and the radial width of the annular floor plates is less than or equal to the corresponding at least one additional annular expansion gap and its corresponding annular gap.

20. A thermal energy storage tank floor according to claim 18, wherein all expansion joints have the same stress-strain curve.

twenty-one . A thermal energy storage tank floor according to claim 18, wherein at least one expansion joint has a different stress-strain curve from at least one other expansion joint.

22. A thermal energy storage tank floor according to claim 21, wherein each radially successive expansion joint has an increasingly steeper stress-strain curve, such that the inner expansion joint exhibits the greatest degree of strain in response to the same stress input.

A thermal energy storage tank floor according to any one of claims 18 to 22, wherein all the annular plates of the floor have the same radial width.

A thermal energy storage tank floor according to any one of claims 18 to 22, wherein the at least one annular floor plate has a radial width that is different from a radial width of the at least one other annular floor plate.

A thermal energy storage tank floor according to claim 24, wherein each successive radially annular floor plate has a radial width that is less than a radial width of its preceding radially annular floor plate, such that the plate Inner annular soil has the greatest radial width.

26. A thermal energy storage tank base comprising: a foundation; and a thermal energy storage tank floor according to any one of the preceding claims, the tank floor resting on the foundation.

A thermal energy storage tank comprising: a thermal energy storage tank base according to claim 26; a cylindrical side wall extending from the tank floor; and a roof supported on the side wall.