Abstract
A device that enables storing in a vessel a fluid at high temperature, in which the fluid is under a coverage gas. The tank has a lower concave head and intermediate zone made by cylindrical rings generated by revolution bodies around the central vertical axis, which contains the level of high temperature fluid that is required to store, and an upper closure made up by an upper head with low altitude to diameter ratio to contain the coverage gas, and supported by the intermediate zone.
Claims
1. A device that enables storing in a vessel a fluid at high temperature, in which the fluid is under a coverage gas, wherein said vessel is made up by a lower concave head and intermediate zone made by cylindrical rings generated by revolution bodies around the central vertical axis, which contains the level of high temperature fluid that is required to store, and an upper closure made up by an upper head with low altitude to diameter ratio to contain the coverage gas, and supported by the intermediate zone.
2. A device that enables storing in a vessel a fluid at high temperature, according to claim 1, wherein the intermediate zone is made by conical sections with an increasing angle between the vertical central axis of the vessel and the conical face, when the cylindrical ring is lower than upper cylindrical ring.
3. A device that enables storing in a vessel a fluid at high temperature, according to claim 2, wherein the intermediate zone is made by only one vertical cylinder with low altitude to diameter ration.
4. A device that enables storing in a vessel a fluid at high temperature, according to claim 2, wherein the upper cylindrical ring of the intermediate zone is made by one vertical cylinder with low altitude to diameter ration, and the lower cylindrical rings of the intermediate zone are conical sections with an increasing angle between the vertical central axis of the vessel and the conical face, when the cylindrical ring is lower than upper cylindrical ring.
5. A device that enables storing in a vessel a fluid at high temperature, according to claim 2, wherein the intermediate zone is made by only one conical section with an angle between the vertical central axis of the vessel and the conical face that is different to zero.
6. A device that enables storing in a vessel a fluid at high temperature, according to claim 1, wherein one of the cylindrical ring of the intermediate zone is made by the revolution body created from a conical section of the vessel and a section of the supporting structure.
7. A device that enables storing in a vessel a fluid at high temperature, according to claim 6, wherein the upper cylindrical ring of the intermediate zone is made by one vertical cylinder with low altitude to diameter ration, and the cylindrical ring immediately below the cylindrical ring is made by the revolution body created from a conical section of the vessel and a section of the supporting structure.
8. A device that enables storing in a vessel a fluid at high temperature, according to claim 6, wherein the upper cylindrical ring of the intermediate zone is made by one vertical cylinder with low altitude to diameter ration and also goes downward as part of the supporting structure.
9. A device that enables storing in a vessel a fluid at high temperature, according to claim 6, wherein one lower cylindrical ring of the intermediate zone is made by a conical section that also goes downward as part of the supporting structure.
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16. A device that enables storing in a vessel a fluid at high temperature, according to claim 4, wherein the upper head is made by a concave head respective to an exit vector to the vessel, with low height to diameter ration.
17. A device that enables storing in a vessel a fluid at high temperature, according to claim 4, wherein the upper head is made by central flat head and an external toroidal concave head.
18. A device that enables storing in a vessel a fluid at high temperature, according to claim 4, wherein the upper head is made by central flat head and an external conical section.
19. A device that enables storing in a vessel a fluid at high temperature, according to claim 18, wherein the upper head is made by central flat head and has an arrangement of flat planes inclined respective to the central axis of the vessel.
20. A device that enables storing in a vessel a fluid at high temperature, according to claim 4, wherein the upper is head is made by central convex head and an external toroidal concave head.
21. A device that enables storing in a vessel a fluid at high temperature, according to claim 4, wherein the upper is head is made by central flat head which is connected with a conical section that goes upward, that is connected with an external annular flat horizontal ring to be externally connected to a conical section that goes downward to be connected with the upper ring of the intermediate zone.
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62. A device that enables storing in a vessel a fluid at high temperature, according to claim 18, wherein the lower zone of the vessel is made by a single concave head.
63. A device that enables storing in a vessel a fluid at high temperature, according to claim 18, wherein the lower zone of the vessel is made by a ring made by a concave shape that is connected to a cylindrical ring that ends with a concave head at the bottom.
64. A device that enables storing in a vessel a fluid at high temperature, according to claim 19, wherein the lower zone of the vessel is made by a single concave head.
65. A device that enables storing in a vessel a fluid at high temperature, according to claim 19, wherein the lower zone of the vessel is made by a ring made by a concave shape that is connected to a cylindrical ring that ends with a concave head at the bottom.
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Description
SHORT DESCRIPTION OF THE DRAWINGS
[0067] To better understand this invention, we provide below a detailed description on the basis of the following figures, which serve the sole purpose of illustrating the preferred way to execute this patent and not to represent a limit to the invention:
[0068] FIG. 1 is a schematic section of the flat-bottomed vertical cylindrical tanks used by commercial plants for storing the molten salts.
[0069] FIG. 2 is a schematic section of the proposed device, made up of the joining of two concave heads that have their axes of revolution vertically oriented, the lower head is a hemisphere or ellipsoid of height to diameter ratio equal to 2, the proposed device has a pumping well, made up by a central downward extension the bottom of which is a lower curved head, the whole vessel is supported from the middle of the lower head, and the higher head contains the ullage gas.
[0070] FIG. 3 is a schematic section of the proposed device, in which the molten salt is contained in 3 cylindrical bodies, a ellipsoidal head at the bottom, a conical section at the middle with the connection to the support system, and a cylindrical section at the top. The ullage gas is contained by an upper head build by combining an external conical section with a central flat heat.
[0071] FIG. 4 is a schematic section of the proposed device, in which the molten salt is contained in 4 cylindrical bodies, a lower ellipsoidal head at the bottom, a conical section over the bottom head with another revolution body on the top that provides a smooth transition to the support system, and a conical section on the top. The ullage gas is contained by an inverted type upper head build by an external toroidal section and an internal concave head.
[0072] FIG. 5 is a schematic section of the proposed device, with a pumping well build by a central downward extension at the center of the lower ellipsoidal head, a conical section at the middle with the connection to the support system, and a cylindrical section at the top. The ullage gas is contained by an upper head build by combining an external conical section with a central flat heat.
[0073] FIG. 6 is a external view of the proposed device, where the upper head to contain the ullage gas is build by central flat head, and an external conical section made by an arrange of faceted inclined planes.
DETAILED DESCRIPTION OF PREFERRED EXAMPLE OF EMBODIMENT
[0074] In this invention a new device is presented that enables to store heat by enclosing a fluid at high temperature, with an inexpensive construction, enabling its application for energy accumulation in the form of molten salt at high temperature.
[0075] FIG. 1 is a schematic section of the vertical cylindrical tanks, typical from the previous state-of-the-art, used by commercial plants for storing heat in molten salts. The tank is made up of a first lower level of a cylindrical body (110), with a vertical axle, of a thickness that enables it to bear hydrostatic pressure and thermal-mechanic stresses, which is then continued by other straight cylindrical bodies (114) and (116) that can be of lesser thickness as the height increases and the hydrostatic pressure and the thermal-static stresses decrease. In this case, the tank is vertically made up by three thicknesses, only for illustrative purposes, but a commercial tank can be made up of a higher number of successive stages of different thickness. The upper head, with the function of containing the ullage gas at slight overpressure, is made up of the curved head (117), while the flat bottom (118) constitutes the watertight base of the tank. The flat bottom (118) transfer the loads and can accommodate its dimensional changes by lying on a sliding surface area (120), which is thermally insulated by the body (122), which lies on the base and on the refrigerated concrete foundations (124), by means of a cooling system that is not shown in the figure, which transmits the load to the surrounding ground (126). The tank is thermally insulated from the external air by means of the cover, (130) and (132). There is schematically shown the vertical pipe (140) of the molten salt pump, the inlet nozzle and impeller (142) of which are located at the lower end of the vertical pipe (140), while the electric motor is located in the upper section (144), together with the molten salt outlet nozzle and pipe (146). Between the lower surface area (150) of the tank bottom (118) and the line (152) of molten salt minimum level is the volume (153) of molten salt, or tank heel, required by the impeller and the inlet nozzle (142) of the salt pump for appropriate operation. There is schematically shown as volume (154) the tank heel of another tank, not shown in the figure, which is required to be stored by the tank that is shown in the figure, for those cases where the contents of the second tank should be emptied for repairs and maintenance purposes. This second volume of tank heel has the upper limit marked-out by the level (155). Above this level (155) is schematically shown the tank volume available to store the heat (156), which has as its upper limit the maximum level of salt in the tank (157). Above this level (157) and the upper head (117), is the coverage or ullage gas (158), which is usually made by dry and clean air, at slight overpressure, as compared to external pressure, to reduce the intake of air impurity and humidity into the salt. In this figure, even though dimensions are exaggerated for illustrative purposes, it can be clearly seen how to the molten salt volume required for heat storage (156) are added the molten salt volumes (153) and (154) generated by the tank heel criterion of a flat-bottomed tank, for defining the total tank and salt volumes required to store heat with this design.
[0076] FIG. 2 is a schematic section of the proposed device, made up of a lower concave head (200), which is schematically shown as a hemisphere and has in its lower central portion a downward extension made up of a cylindrical body (202) with a lower cover made up of a concave head (204). The lower central extensions (202) and (204) contain the tank heel (210) or pumping well, and the molten salt level of which is schematically shown as the line (212). Should it be required to transfer, to the tank shown in FIG. 2, the tank heel from the second tank, not shown in the figure but of similar shape than the tank shown in FIG. 2, this salt volume (214) also results from a very low upper limit (216), given the concave shape of the head (200). Above these two heel levels is the molten salt volume required for storing the heat (217), the upper limit of which is schematically shown as the line (218). Above the line of maximum salt level (218) is the ullage gas (220), which is enclosed by the upper concave head (222). In the figure, the lower head (200) is schematically shown as of thickness significantly higher than the upper head (222), since the first has as design pressure the pressure of the hydrostatic column of molten salt, while the second has as design pressure the slight overpressure required to secure that no air impurities and humidity enters into the ullage gas and be able to support its own weight and any mechanical device attached to the vessel head. Both the lower head (200), including its tank heel, (202) and (204), and the upper head (222) are covered by a thermal insulation (230) (232) (234) and (236) to reduce the thermal losses to the external air. The lower head (200) is supported by a support system (240) made up of sliding supports (242) and (244) typical for pressure vessels, selected for bearing the whole weight of all the molten salt and the vessel, at the molten salt temperature. A lower structure (250) and a local thermal insulation (252) enable to transfer the loads to a supporting structure (254) at ambient temperature, which finally transmits the load to the ground (256). Since the sliding supports (242) and (244) enable to freely dilate the tank in the radial direction, while the bottom of the tank heel (204) and its thermal insulation (234) have a given clearance from ground level (256), the proposed device enables the tank to freely dilate in an axial and radial directions. These characteristics allow to absorb the dilatations, with no mechanic stress taking place, in the tank or its supports, ensuring that the loads are within the load range of the vessel support standards. The device also requires a low metal weight for the whole tank assembly, since a hemisphere requires approximately half the weight, per contained volume, than a full sphere, provided the fluid is subject to an upper pressure similar to atmospheric pressure, because in that case design pressure is mainly given by hydrostatic pressure. For illustrative purposes, and as the tank heel, (202) and (204), is centered on the bottom of the lower head (200), the pump extracting salt from the tank is schematically shown as a single pump (260), but in the specific designs there can be present several pumps, not shown in the figure but all of them submerged into the tank heel, (202) and (204). It can be qualitatively noticed how the salt volume of the two tank heels of this device (210) and (214), is comparatively much smaller than the volume of the tank heels (153) and (154) of the flat-bottomed cylindrical tanks, like those shown in FIG. 1, commercially used at present. The shape of the lower head (200) that contains the molten salt above the lower heal (210) and (214) and below the level line (218) required a bi-dimensional shaping of the metal sheets at all the submerged surface of the head (200), which will increase the cost of the curved metal sheets, joint machining, alignment and welding, in such a way that even considering the concave shape will require a small thickness for the metal sheets, the manufacturing cost could jeopardize the final cost of the vessel build by a single main concave head.
[0077] FIG. 3 is a schematic section of the proposed device even cheaper to build than the design alternative of FIG. 2, to store the molten salt (300), with is fluid maximum level line (302) between the lower line (304) and the upper line (306). Below the lower line (304) is the concave lower head (310), while above the lower line (304) and the upper line (306) the intermediate body of the vessel is made by 2 revolution rings (320) and (325), to simplify the explanation, but the intermediate body of the vessel could be made from a single revolution ring to several revolution rings to reduce the vessel manufacturing costs. The upper revolution ring (325) is a vertical cylinder with reduce manufacturing cost because the design pressure is given by the hydrostatic pressure produce the difference in height between the higher level line (302) and the height of the bottom end of the cylinder (325). The lower revolution ring (320) is made by a conical section to have a reduced manufacturing costs in addition to give structural support to the union between the vessel and the support structure and withstand the hydrostatic pressure give by the height difference between the higher level line (302) and the height of the bottom end of the cylindrical cone (320). The revolution rings (320) and (325) of the intermediate body have low manufacturing cost because have low thickness and requires shaping in a single direction, applying only to the lower head the two dimensional shaping required for a concave head, and where the thickness is keeping low due to the inherent resistance of concave bodies subject to internal pressure produced by the higher hydrostatic pressure, and without needing to be able to support the concentrated loads produced by the support system. The vessel support system (330) is connected with one of the rings of the revolution ring of the intermediate zone, in this case shown as the ring (320), to transfer the load to the civil structure (335), that finally transfer the load to the ground (340). The ullage gas (350), above the upper line (306) is enclosed by an upper head build by an external conical section (360) and a central flat head (365). This upper head have low manufacturing cost by the inherent nature of the shape to support its own weight, the weight of the molten salt pumps (367) and (368), and the very small overpressure required in the ullage gas to compensate the any small leakages in the upper vessel head. All the vessel is covered by a thermal insulator (370) (372) (374) and (376) to reduce the thermal losses to the ambient air. The supporting device (330) has its own thermal insulation (378) to ensure that the thermal stress are compatible with the union between the supporting device (330) and the civil structure (335).
[0078] FIG. 4 is a schematic section of the proposed device to store the molten salt (400), with is fluid maximum level line (402) between the lower line (404) and the upper line (406). Below the lower line (404) is the concave lower head (410), while above the lower line (404) and the upper line (406) the intermediate body of the vessel is made by 2 revolution rings (420) and (425), with a revolution body (427) that connects the revolution rings (420) and (425) with the supporting structure (430). The intermediate body of the vessel is made by two revolution rings to simplify the explanation, but the intermediate body of the vessel could be made from a single revolution ring to several revolution rings to reduce the vessel manufacturing costs. The support structure (430) transfer the loads to the civil structure (435), that finally transfer the load to the ground (440). The ullage gas (450), above the upper line (406) is enclosed by an upper head build by an external toroidal section (460) and a central concave head (465). This upper head have low manufacturing cost by the inherent nature of the shape to support its own weight, the weight of the molten salt pumps (467) and (468), and the very small overpressure required in the ullage gas to compensate the any small leakages in the upper vessel head. All the vessel is covered by a thermal insulator (470) (472) (474) and (476) to reduce the thermal losses to the ambient air. The supporting device (430) has its own thermal insulation (478) to ensure that the thermal stress are compatible with the union between the supporting device (430) and the civil structure (435).
[0079] FIG. 5 is a schematic section of the proposed device to store the molten salt (500), with is fluid maximum level line (502) between the lower line (504) and the upper line (506). Below the lower line (504) is the concave lower head (510), while above the lower line (504) and the upper line (506) the intermediate body of the vessel is made by 2 revolution rings (520) and (525). The intermediate body of the vessel is made by two revolution rings to simplify the explanation, but the intermediate body of the vessel could be made from a single revolution ring to several revolution rings to reduce the vessel manufacturing costs. The upper revolution ring (525) is a vertical cylinder with reduce manufacturing cost because its design pressure is given by the hydrostatic pressure produce by the difference in height between the higher level line (302) and the height of the bottom end of the cylinder (325). The lower revolution ring (520) is made by a conical section to have a reduced manufacturing costs in addition to give structural support to the union between the vessel and the support structure and withstand the hydrostatic pressure give by the height difference between the higher level line (502) and the height of the bottom end of the cylindrical cone (520). The revolution rings (520) and (525) of the intermediate body have low manufacturing cost because have low thickness and requires shaping in a single direction, applying only to the lower head the two dimensional shaping required for a concave head, and where the thickness is keeping low due to the inherent resistance of concave bodies subject to internal pressure produced by the higher hydrostatic pressure and without needing to support the concentrated loads produced by the support system. Below the bottom line (580) the lower head (510) ended y a new volume (582) of molten salt that makes the tank heel or pumping well, build by a cylindrical ring (585) and a small lower head (590), with its molten salt level given by the line (580). The vessel support system (530) is connected with one of the rings of the revolution ring of the intermediate zone, in this case shown as the ring (520), to transfer the load to the civil structure (535), that finally transfer the load to the ground (540). The ullage gas (550), above the upper line (506) is enclosed by an upper head build by an external conical section (560) and a central flat head (565). This upper head have low manufacturing cost by the inherent nature of the shape to support its own weight, the weight of the molten salt pumps (567) and (568), and the very small overpressure required in the ullage gas to compensate the any small leakages in the upper vessel head. All the vessel is covered by a thermal insulator (570) (572) (574) (576) (592) and (594) to reduce the thermal losses to the ambient air. The supporting device (530) has its own thermal insulation (578) to ensure that the thermal stress are compatible with the union between the supporting device (530) and the civil structure (535).
[0080] FIG. 6 is a external view of the proposed device, where the thermal insulations and surrounding ground is not shown, in which the intermediate body is made by a upper vertical cylinder (600) and a lower cylindrical cone (610), connected to a support skirt (620), and the lower body is made by the concave head (625). The support skirt (620) transfer the loads to the civil structure (630), made by pre casted-bodies, which transfer the loads to the pre-casted foundations (635). The ullage gas is closed by the upper vessel head made by a short cylindrical vessel head (640), and azimuthally arranged of flat planes to resemble a conical section, as the flat plane (650), and a central flat head (660) at the center and the top. Pumps and other opening to the upper vessel head are arranged in the central flat head (660) and also in several flat sheets, as the flat sheet (650) but without any specific identification line, because are only shown as a schematic example of the loads that needs to be considering when the upper head is designed.
[0081] Following, 117 claims are provided on pages 21 to 29:
