AU2009286256B2

AU2009286256B2 - Floating structure of concrete

Info

Publication number: AU2009286256B2
Application number: AU2009286256A
Authority: AU
Inventors: Arnstein Godejord
Original assignee: VSL International Ltd; Samsung Heavy Industries Co Ltd; Floating Storage Concept AS
Current assignee: VSL International Ltd; Samsung Heavy Industries Co Ltd; Floating Storage Concept AS
Priority date: 2008-08-25
Filing date: 2009-08-24
Publication date: 2013-08-15
Anticipated expiration: 2029-08-24
Also published as: BRPI0917918A2; WO2010024685A8; AU2009286256A8; AU2009286256A1; BRPI0917918B1; NO20083648L; WO2010024685A1; NO335458B1

Abstract

Floating concrete structure (1), preferably for storing oil, comprising a substantially torus shaped shell structure (2) having internal radial walls (15) and a upwardly and downwardly curved dome shaped shell structure (7, 8) closing the open centre area of the substantially torus shaped shell structure, above and below, respectively.

Description

H:\zn erwoven\NorbhDCC\TZ\53 123 1 _do-1607/2003 Floating concrete structure The present invention concerns a floating concrete structure, preferably for storing oil. 5 The floating structure can also in addition to be an oil storage be provided with for example oil and gas processing equipment and thus function as an offshore floating oil and gas platform. The structure can also function as a floating body alone, accordingly without storage function. NO 147591 B describes a device in the form of a floating body which is formed to 10 reduce pitching, rolling and submerging of the body. The body which can be a floating platform or an oil storage, can be formed as an annulus. The body is formed with an internal closed ring where the stored material can float freely. The annulus itself is encircled by a cylindrical wall extending above the water surface and also down below the water surface. In the bottom of the floating body substantially vertical, downwardly open 15 and in other respect closed chambers are provided which in the floating condition are completely filled with water, whereby the mass of inertia of the body is changed. NO 320663 Bl describes a floating cylindrical oil storage having a cylindrical centre section and tank sections which all are connected to the central section containing pipe systems. The object of this structure is mainly to optimise the pipe system connecting 20 the tanks in a tank arrangement of this particular type. Preferred embodiments of the present invention may provide a concrete oil storage which can be constructed based on effective construction methods and hence is economical competitive with today solutions. Preferred embodiments of the floating structure may exhibit good hydrodynamic 25 characteristics under all sea conditions. In this connection it is important to avoid that the period for heave and pitch (accordingly vertical movement and rotation) respectively is not to strongly connected together such that these movements are increased. According to preferred embodiments, the floating structure is provided with a favourably shape with regard to strength such that for example differential pressures acting 30 on walls are relatively low.

H a ~merwovn\NRPonbDCC\TZ53 1223_1 doc-16/07/2013 -2 According to preferred embodiments the floating structure shall be flexible, i.e. in addition to be an oil storage it shall also in a simple way could be provided with required equipment and this function as an offshore oil and gas platform. According to the present invention there is provided a floating concrete structure 5 preferably for storing oil, comprising a substantially torus shaped shell structure having internal radial walls and a upwardly and downwardly curved dome shaped shell structure closing the open centre area of the substantially torus shaped shell structure, above and below, respectively. Preferred embodiments of the floating structure are further described in the 10 following description and claims 2 - 8. A preferred embodiment of the invention shall now be explained with reference to the attached drawings, where figure 1 depicts a floating structure having a deck structure mounted on, figure 2 depicts a floating structure of figure 2, but now with a part of the upper 15 shell structure removed. The floating structure is here shown without the deck structure, figure 3 depicts a plan view of the floating structure, figure 4 depicts a front view of the floating structure in a operational phase with empty tanks, figure 5 depicts a floating structure now in a operational phase with full tanks and 20 figure 6 depicts a plan view of the floating structure where the internal tanks having another form than in figure 3. With reference to the figures a floating structure 1 of concrete is shown. The structure I includes storage tanks for oil and is shown with a possible deck structure in figure 1. 25 The floating structure I has a torus shaped shell structure 2 which in the shown embodiment is substantially ring formed with an outer and inner cylindrical wall 3, 5. The outer and inner cylindrical walls 3, 5 are in their upper area connected to a upwardly curved torus part 10 and in the lower area connected with a downwardly curved torus part I1 thus closing the torus formed shell structure 2. The substantially torus shaped shell 30 structure 2 is provided with internal radial WO 2010/024685 PCT/N02009/000295 3 walls 15, and in this connection references are particularly made to figure 2 and 3. The torus shaped shell structure 2 is provided with a upwardly and downwardly curved dome formed shell structure 7, 8 closing the open centre area of the substantially torus shaped shell structure, above (in the upper parts) and below (in 5 the lower parts), respectively. The outer cylindrical wall 3 of the shown embodiment has a double shape including transversal bulk heads 4. It should in this connection be mentioned that double hulls are required for such installations. The double shape of the wall 3 provides chambers which for example can be ballasted in order to adjust the 10 freeboard of the floating structure during different operational conditions. In the depicted embodiment the internal radial walls 15 have a height equal to the outer and inner cylindrical walls 3, 5. It should be mentioned that the internal radial walls 15 either can start higher up or end lower down. The main object of the radial walls 15 is to provide global stiffness and to prevent "splashing" within the 15 storage volume. The radial walls 15 are provided with internal transversal bulk heads 16. Figure 6 depicts another embodiment of the internal radial walls 15 which also here has a double shape with a first and a second wall 17, 18. The walls 17, 18 are curved in each direction in relation to a radial centre axis 20. 20 The internal radial walls can also be provided with throughgoing openings. The geometrical form of the floating structure I is a result of a number of design criteria as for example requirement to: stability, strength with regard to acting water pressure etc., safety with regard to collision from for example ship, minimal weight and draft and effective construction methods as for example tunnel 25 formwork, slip casting, prefabrication of segments etc. On the basis of the above discussed criteria the optimum solution is a floating structure 1 consisting of a substantially torus formed shell structure 2 having a upwardly and downwardly curved dome shaped shell structure 7, 8 or spherical shell closing the open centre area, above and below, respectively of the 30 substantially torus formed shell structure. Inside the storage itself radial walls 15 are provided which take care of "sloshing-forces" and ensure global stiffness and strength. In the shown embodiment the internal radial walls 15 terminate at lower and upper ring beam elevation, such that oil freely flows under the walls inside the H:\tzslnnoven\NRPortb O\TZS\5312238_l doc.-16A/2013 -4 torus form. The solution of the torus shape and the radial walls 15 extending not completely down allows the fluid to freely flow in the bottom of the tank such that the complete volume is to be regarded as a large tank (free liquid surface). This provides the floating structure 1 with an acceptable relation between natural period for vertical 5 movement and rotation in floating condition whereby hydrodynamic problems are avoided and good stability is achieved. The geometrical form of the floating structure I with the different shell formed domes, torus and cylinders takes care of the water pressure in an effective way. Further, a very simple rotational symmetrical load distribution is achieved and accordingly reinforcing arrangement which results in a cost effective manufacture of 10 the floating structure 1. Figure 4 depicts the floating structure I in an operational condition with empty internal storage tanks. With regard to stability of the floating structure 1 the internal storage tanks will be filled with liquid up to the shown level. Figure 5 depicts the floating structure 1 in a operational condition with full internal 15 storage tanks. The floating structure I floats high in the water when the internal storages are empty and lower in the water when the internal storages are filled up. In both cases the differential pressures across the walls are relative minor. An embodiment of the floating structure 1 is discussed above, but it should be 20 understood that the floating structure may have other forms, for example a "more complete" torus shaped shell structure 2 without the outer and inner vertical walls is possible. The internal radial walls may also have another form than in the shown embodiment. While various embodiments of the present invention have been described above, it 25 should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments. 30 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and H mlicrovn. \NRPonb\DCCTZSIS1223#_1do-16B11/201 -5 "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived 5 from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

1. Floating concrete structure for storing oil, comprising: a substantially torus shaped shell structure having internal radial walls and a upwardly and downwardly curved dome shaped shell structure closing the open centre area of the substantially torus shaped shell structure, above and below, respectively.

2. Floating structure according to claim 1, wherein the substantially torus shaped shell structure is a substantially ring formed shell structure having an outer and inner cylindrical wall connected to a upwardly curved torus part in their upper area and to a downwardly curved torus part in their lower area.

3. Floating structure according to claim 2, wherein the outer and inner cylindrical walls are vertical.

4. Floating structure according to claims 2 or 3, wherein the internal radial walls having a height equal to the outer and inner cylindrical walls.

5. Floating structure according to any one of the preceding claims, wherein the internal radial walls having double shape with internal transversal bulk heads.

6. Floating structure according to claims 2, 3, 4 and 5, wherein the outer cylindrical wall having double shape including transversal bulk heads.

7. Floating structure according to claims 1, 2 or 3, wherein each of the internal radial walls having double shape, a first and second wall respectively, where each wall is curved in each direction in relation to a radial centre axis.

8. Floating structure according to any one of the preceding claims, wherein the internal radial walls are provided with throughgoing openings.