Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D88/00—Large containers
  • B65D88/78—Large containers for use in or under water

Definitions

• the present invention relates to fluid storage and provides a simple construction of storage device which can float freely in a liquid denser than the fluid to be stored.
• a fluid storage device to be floated in a liquid the density of which is greater than the density of the fluid to be stored, comprising an open-bottomed container which has when floating a centrally disposed vertical axis coincident with the line of action of the resultant buoyancy force acting on the device, and which is provided with ballasting and with buoyancy equipment disposed uniformly about the axis to maintain the device, when free floating in the liquid, in a uniform attitude with its open bottom downwards irrespective of the held quantity of the stored fluid, the buoyancy equipment restoring said attitude after disturbance but being insufficient of itself to maintain the device floating,
• the ballasting may be constituted by the general structure of the device or by added dense material, preferably low down to aid stability.
• the buoyancy equipment or more descriptively buoyancy/balancing equipment, may consist of any structures extending from below to above the level of the surrounding liquid that will, if the uniform attitude of the device is disturbed, displace more of the liquid in which the device is floating on the side which has become lower than on the side which has become higher, and thus generate a righting force.
• Preferably such structures are of uniform cross-section.
• a series of vertical closed empty box sections at or near the periphery of the container is often convenient, but the restoring force (assuming a uniform cross-section in individual units of the buoyancy equipment) will depend only on the relative depth of immersion from one side of the container to the other, determining the differential volume of the surrounding liquid displaced. Buoyancy in the ordinary, loose sense of flotation, using a material less dense than the surrounding liquid, is thus not the point but true buoyancy forces due to displacement.
• the units can in fact be in dense material such as concrete, for example as cylinders extending downwards from the superstructure of a sludge digester cap/gasholder for partial immersion in the slurry, and in such an instance the device is floated by its contained gas. Where dense materials are used they generate righting forces not only from differential buoyancy but further through the excess of material above the surrounding liquid level at one side compared with the other, the weight of which also gives a restoring force.
• the buoyancy units can be of concrete or other dense material throughout in a large device where the weight of the volume of material involved does not exceed that required for ballasting. In a smaller device the displacement volume required for the buoyancy/balancing function will be such that part filling of the units with dense material gives the required ballasting and the remaining part is left empty or filled with low-density material.
• buoyancy units may take no significant part in the ballasting of the device, being empty or fitted with low-density material, and the ballasting may be separate.
• any hollow sections forming part of the buoyancy units should be filled with material, for example in-situ closed-cell plastics foam, that will, ensure that a damaged section cannot take in the surrounding liquid and unbalance the device.
• the degree of movement allowed in the device about its rest position will vary with its weight and size, with the minimum working distance required between the level of the open bottom and the level of the surrounding liquid, and thus for example with open water or virtually fixed land use.
• a sludge digester for example while essentially free floating, may be constrained by external guides and if desired have no more clearance from the walls of a surrounding enclosure or pit than is necessary for free movement without jamming by solids present in the sludge. Nevertheless the righting forces of the invention will act on it and oppose tilting and jamming in its pit or guides by wind forces for example.
• the device of the invention may, for example, be cylindrical with a closed top and open bottom, or for example rectangular in plan, and conveniently the closed top is peaked by being for example right conical in the case of the cylindrical form or right pyramidal in the case of the rectangular form of container.
• the device may have associated with it additional flotation equipment, e.g. free flotation rings surrounding
• ⁇ DREA ?* OMPI it or high mounted box sections to assist to prevent the device from sinking when empty of the fluid to be stored.
• the device may rest when empty on a solid bottom for example by means of downwardly projecting legs, which may for example if required be formed as part of combined ballasting and buoyancy equipment.
• the devices other than the ballasting, can be relatively light-weight structures and may be plain or braced internally or of honeycomb or laminated construction.
• ballasting and buoyancy equipment of a device of the invention are so designed that the device will not float when void of a light fluid.
• a quantity of the fluid must be collected £>efore the device becomes free floating and also additional support is required when the device is void of light fluid.
• the device maintains a uniform attitude with respect to a vertical through the centre of lift irrespective of the quantity of fluid stored.
• Fig. 1 is a diagrammatic perspective of one embodiment
• Fig. 2 is a plan of it to a smaller scale
• Fig. 3 shows a second embodiment, in underneath perspective view
• Fig. 4 shows in part the embodiment of Fig. 3 in section
• Figs. 5 and 6 show an embodiment similar to Fig. 3, empty of stored fluid and full respectively,
• Fig. 7 shows a further embodiment in cut-away
• Fig. 8 shows a still further embodiment in section.
• the form of storage device 10 illustrated is hollow and cylindrical, being open at its bottom and closed by a conical top 11 whereof the cone angle is slightly less than 180° and the apex 12 projects upwardly.
• a shallow conical space is provided within the device above the plane of the top edge of the cylindrical wall.
• ballasting and buoyancy members 14 Distributed around the axis of the cylindrical device are a plurality of ballasting and buoyancy members 14 so that when the device is floating in a liquid 15 its axis will remain substantially vertical.
• each form comprising a long closed hollow tube secured parallel to the axis of the device to provide buoyancy and at the bottom of the tube ballasting 16.
• members 14 may project below the device 10 to provide legs limiting the depth to which the device may sink, e.g. by engaging the ground below the liquid or special hard standing below the surface.
• the members 14 may be wholly within the device 10, which rests on a supporting ledge below the surface when at its lowest in the liquid 15.
• the illustrated embodiment is a container 20 rectangular in plan, the container being open at its bottom and having a closed top 21 of right pyramidal form with a large apex angle.
• This form of device has ballasting, shown in the form of bars 22 secured to the bottom edges of the device, and buoyancy equipment formed by closed chambers 23 at the corners of the rectangle, the arrangement being symmetrical about a vertical through the apex 21a_ of the top 21 so that, when floating, the axis is maintained vertical.
• a device as just described which is 5 metres long, 3 metres wide and 1 metres deep has its buoyancy equipment designed to give lift equivalent to about 20% of the total displacement of the device, so that when sufficient light fluid, e.g. gas, is contained to enable the device to float free, the pressure induced on the gas is about 20 cms and, when containing its maximum design volume of light fluid, the induced pressure is equivalent to a head of about 25 cms of the liquid.
• sufficient light fluid e.g. gas
• Fig. 4 shows the device floating in a liquid 15 and substantially filled with a less dense fluid 26, e.g. a gas, under a liquid head as indicated by arrows 27.
• a less dense fluid 26 e.g. a gas
• the device due to the ballasting and buoyancy means, floats in the liquid in a uniform attitude, i.e. with its central axis substantially vertical.
• Storage devices as described with reference to Fig. 3 may if desired be accommodated in a barge for transfer to and from a fluid collection position.
• a barge may for example have a pivoted stern section forming a door giving access to a load space into which the devices are floated.
• one or more devices may simply have shaped bow and stern sections attached.
• the barge may be open bottomed in the part accommodating the storage devices or if desired, to separate the contained fluid from the surrounding liquid during transport, the barge may have a closed hull bottom, or a
• OMPI removable or retractable closure e.g. of the roller shutter kind.
• the device is generally in the form of a water craft but with an open bottom which can be closed for transport by means of roller shutters or pivoted vane shutters for example.
• Figs. 5 and 6 show a device such as that of Fig. 1 or Fig. 3, with another form of ballasting 30 in this case of a skirt of saturated concrete. Also shown is auxiliary means for preventing the device from sinking below a selected depth when no light fluid is stored; this means comprises free floating buoyancy devices 31 which when the storage device 20 is empty are engaged by flanges 32 projecting from the device 20. Such free-floating devices 31 are especially suitable when the depth of the liquid 15 ' is large and may alternatively be mounted permanently, high on the device to be normally out of the water.
• Fig. 7 there is illustrated one unit of a digester matrix eight units by ten and of total slurry capacity
• Each unit has a ring beam at the base in which a ballast skirt 101 of reinforced concrete cast in situ in an upturned rim is continuous with concrete-filled buoyancy/balancing zones 102 at the corners. These zones are 0.4 m square.
• the main structure is of glass reinforced plastics with a shallowly pyramidal roof and has box sections
• FIG. 8 which shows one side of a circular sludge digester tank installation in vertical section
• the concrete of a containing pit is shown at 201, with an optional side wall 201a forming a water seal.
• a cap/gasholder 202 has a steel roof frame 203, a steel side wall 204, and plastics roof-panelling sections 205, with 100 mm foamed polyurethane' insulation, suspended from the roof frame.
• Guide/wheel structures 206 locate the cap/gasholder with ample clearance in the water seal where used or between the pit wall and cap/gasholder side wall if not.
• Tie rods 207 to the centre of the roof frame are provided, and resting pads 208
• the swept volume is 460 , the rise 2.575 rn, contained gas pressure ca. 150 mm water gauge at beginning of rise, ca. 200 mm at full rise, as indicated by the water seal level difference at A.
• OMPI Buoyancy balancing on the principle of the invention is provided by twelve equidistantly spaced reinforced- concrete ballast weights 209 suspended from brackets 210.
• the devices of the invention are primarily for gas or other fluid collection and storage they have other uses in which the storage is temporary or incidental to the main purpose.
• the devices can be used as flotation units that are stable when they reach or while they are at the surface.
• the devices can be used as floating working platforms. They are especially suitable, as described above, as covers of anaerobic digesters for collecting and storage of gas produced in the digester. Such gas is usually burnt and the device enables the gas to be stored and drawn off when required at a rate greater than it is generated.
• the devices may also be used to collect and store oil or gas issuing from the sea bed or rising from a sunken vessel.
• individual units may be linked together to form a matrix.
• a matrix may cover a very large area, individual units being deflatable where necessary for servicing or other attention
• moving units In moving units they may be inflated to the brim to minimise draught and allow passage through shallow water or swamp, and extraction in swamp conditions after use as for example a working platform gives no difficulty, there being no underside in contact with the surface to give suction adhesion difficulties.
• a suitably strong skirt simply cuts into the surface, and the units may be pressurised if necessary for release.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Revetment (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10516402

Family Applications (1)

Country Status (4)

Citations (8)

• 1981
  • 1981-09-30 EP EP81304525A patent/EP0049168A3/en not_active Withdrawn
  • 1981-09-30 BR BR8108817A patent/BR8108817A/pt unknown
  • 1981-09-30 JP JP56503104A patent/JPS57501574A/ja active Pending
  • 1981-09-30 WO PCT/GB1981/000205 patent/WO1982001178A1/en not_active Ceased

Patent Citations (8)

Also Published As

Similar Documents

Legal Events