DE2262304A1 - INSIDE STORAGE TANK - Google Patents

Description

Dr.-lng. E. BERKENFElO · Dipl.-Ing. H. BEkKENFELD, patent attorneys. Cologne Attachment file number

for input from ^, December 1972 ya / 1 Named. Ann. Chicago Bridge

& Iron Company

Storage tank near the coast

The invention relates to tanks for storing liquids. The invention particularly relates to an offshore storage tank that is towed to a stand and sunk can to rest on the ocean floor, and the one to save liquid materials, including liquid hydrocarbons, can be used which have a specific gravity which is less than the specific gravity of fresh water and seawater, as well as storing heavier liquids.

Large quantities of oil are obtained from offshore wells, from many of which are a few kilometers from the nearest coast. While the oil from such wells can be piped to shore for storage, it generally is more convenient and economical if the oil is stored in the vicinity of the producing well until the accumulated Amount of ftyr is enough for a tanker to take in the oil and the same transported to a chosen destination.

Many types of constructions have been proposed, and a considerable number are actually built and for offshore use Storage of liquid hydrocarbons, such as oil, been used. Many of the storage tanks are named, however expensive to manufacture and to an offshore stand too transport to be submerged on the ocean floor. After sinking, the tank close to the coast must be strong enough to handle the to withstand the expected maximum storm influence while the tank is in use at the stand. In general such tanks must be designed in such a way that they provide adequate

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have structural strength in order to be able to stand at the place where the Tank is arranged on the ocean floor, the storm influence generally occurring after a hundred years of experience resistance Afford. In addition to meeting such requirements, an offshore tank must be able to handle the oil at the lowest possible cost absorb and store per liter that are compatible with safety and good ecological practice.

The invention provides a storage tank close to the coast, which is essentially completely built on the coast or in a corresponding coastal area and then to a coastal area Stand can be towed to be submerged on the ocean floor. The offshore tank according to the invention can be a large storage capacity at a comparatively low cost per unit of storage volume because of the relative simplicity of its Have training. The tank has a circular cylindrical vertical shell, which can be selected from any suitable Material, but conveniently made from metal plates. However, the jacket can also consist of concrete. The tank has a continuous horizontal rigid floor containing solid ballast and connected to the shell. The floor is in essentially level and can rest on the ocean floor at a stand where the tank is sunk for use. The vertical Mantle is made large enough or high enough to extend from the sea floor to a height above sea water level sufficient to hold fresh water, sea water or any other liquid with a liquid level above it of the surrounding sea water level to apply a net downward pressure to the bottom of the tank. The combined weight of the tank plus the pressure created by the height of the liquid in the tank above sea water level If the impact occurs, it must be sufficient to keep the tank under the influence of a storm to be held in position at a stand where the tank is located. In addition, the vertical jacket is only available when supplemented Due to the internal fluid pressure, able to withstand the storm without buckling and collapsing when the tank

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resting on the ocean floor * Without such a liquid level The jacket in the tank is not strong enough to withstand the storm to resist. Of course, the jacket is strong enough and provided with adequate ballast to withstand the pressure to resist the sea water in non-stormy weather, when the internal liquid level is approximately the same as the sea water level.

If the coastal storage tank is to be used for storing a liquid hydrocarbon, the tank is provided with a device for supplying a liquid hydrocarbon and for discharging the same from the tank, as well as with a device for supplying water and for discharging the same from the tank. Both devices, however, are operable to effect the desired exchange of liquids in the tank while at the same time keeping the interior of the tank filled with liquid at least to a level above sea water level to exert a substantial downward pressure on the tank bottom which is sufficient to hold the tank in place under the influence of storms. The vertical shell of the tank m is capable only when supplemented by the internal fluid pressure to do the storm influence without Einknikken and folding resistance when the tank rests on the seabed.

In one embodiment, the bottom of the tank is expediently provided with a horizontal metal plate, which with the circular vertical cylindrical metal jacket is connected. A layer of solid ballast material, such as concrete, is on top placed on the top of the metal plate, which is part of the Bo-. dens forms. It is also useful that a metal plate the top of the ballast layer is placed and that this upper metal plate with the circular vertical cylindrical Coat is connected. In addition, the ballast layer is expediently reinforced in order to obtain additional strength. Finally connect The ballast layer appropriately with the metal plates arranged above and below the same, as well as with the binder

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circular vertical cylindrical mantle.

Since the tank according to the invention is made with a considerable size is to be, for example with a diameter of at least 30 m, the vertical metal jacket is expediently made of a Series of horizontal metal rings made of metal plates. The thickness of each ring can be even with Except for the panels that are used around openings or the like where heavier panels are sometimes desirable for added strength. The rings of the mantle, which of the Are subject to wave action, but are suitably made thicker and thereby stronger than the other rings, so that the tank can more easily withstand the forces acting during storms. By using thinner metal plates for the lower rings, less expensive material is required and manufacturing costs are reduced.

To prevent excessive bending or out-of-rounding To support a circular cylindrical vertical metal jacket, horizontally arranged, spaced stiffening rings can be used connected to the inside of the jacket. In contrast to out-of-rounding, that is the strength of the tank is not affected, the level of liquid maintained in the tank is necessary to prevent the tank shell from buckling and collapsing to preserve, even if it allows out-of-rounding. Of course, this is a problem with a concrete casing is less of a problem as it is much less flexible than a metal jacket.

An enclosure can be placed vertically so that it extends from the bottom of the tank bottom down into the sea floor extends to the eroding of the seabed material below to prevent the bottom of the tank. In particular, the skirt is arranged so that it extends from the lower outer edge of the vertical Mantle extends downwards. The bezel is pushed into the seabed when the tank is sunk to open on the sea.

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resgrund to rest.

The tank can be left open at the top or it can be arched with a fixed roof or conical shape. In addition, a substantially flat roof occupying a fixed position can be used will. Such a fixed position roof can be on the upper part of the circular cylindrical vertical jacket are arranged. A floating roof can, however, on the inside of the vertical cylindrical shell with or be used without a fixed outer roof. However, since the tank with a liquid above the level of the surrounding sea water level must be kept filled, the vertical displacement of the floating roof is appropriately limited, so that it does not move substantially below sea level when the tank is in operation. About a free vertical shift to enable a floating roof on the liquid in the tank when the vertical jacket with inner, im Spaced stiffening rings is provided, it is advisable to Above the stiffening rings in the upper part of the vertical shell of the tank a cylindrical metal ring for guiding the To arrange floating roof.

A storage tank close to the coast is therefore characterized according to the invention by a circular cylindrical vertical jacket and by a continuous one connected to the jacket horizontal rigid floor containing solid ballast and on which The sea bed can rest, the vertical mantle being large enough to move above the sea water level when the bottom rests on the sea bed to be able to protrude with a height that corresponds to the height of a "liquid, which the jacket in the filled state Can contain up to a liquid level above sea water level, along with the pressure of the tank weight to exert adequate pressure to hold the tank in position under the influence of storms at a location where the tank is located should be arranged, and with the vertical jacket only at

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Resistance to storm influence by the internal fluid pressure can afford without collapsing when the tank rests on the ocean floor.

The invention is described below with reference to the drawings described in more detail in which shows;

1 shows a vertical longitudinal section of a storage tank near the coast according to the invention, which has an open top and a floating roof,

Fig. 2 shows a partial longitudinal section of the floor on a larger scale of the storage tank near the coast according to FIGS. 1 and

Fig. 3 is a vertical longitudinal section of another embodiment of the coastal storage tank according to the invention, the rests on the seabed and has a fixed roof.

as possible are the same parts or elements that are identical and appearing in the various figures of the drawings are denoted by the same reference numerals.

According to FIGS. 1 and 2, the storage tank 10 close to the coast has a vertical cylindrical metal jacket or wall 11 which is made up of a plurality of horizontal rows or rings of metal plates. Each ring is circular in horizontal cross-section and can be of any suitable height, but will generally be 1.8 to 3.0 meters high. Any number of such rings can be used to make the vertical cylindrical mantle as high as desired, but at least high enough to extend substantially above sea water level at a location in which the tank is to be submerged. The bottom of the tank 10 has a lower horizontal metal plate 12 and an upper horizontal metal plate 13, both of which extend over the area from the vertical

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Sheath 11 is enclosed. Between the lower plate 12 and the Upper plate 13 is placed concrete, which forms the ballast material. Enough ballast is used to keep the tank on the ocean floor to be firmly anchored if it is sunk. The tank contains a liquid up to a height above sea water level, which is sufficient to prevent the tank jacket from collapsing under the influence of storms.

A variety of stiffening rings 15 made of metal can be on the Inside of the vertical jacket 11 are arranged at a horizontal distance relative to each other. The stiffening rings can, however can also be attached to the outside of the jacket. A skirt 16 made of metal plates is around the lower one Arranged bottom part of the vertical metal jacket. The mount extends a considerable distance below the bottom plate 12 so that it can penetrate into the seabed when the tank is sunk to rest on it. Between the Cement mortar 17 is placed on the skirt 16 and the vertical mantle 11 to hold the skirt firmly in place before the tank is sunk. . -

A floating roof 19 is slidable in the vertical direction with the rise and fall of the liquid in the tank. A vertical one Ring 18 of metal plates is placed in the upper inner part of the vertical shell 11 around a cylindrical wall to form, which has a smooth surface on which the circular floating roof 19 during the vertical displacement can slide without hindrance.

A standpipe 20 is connected at its lower end 21 to the inner floor space of the tank 10. The upper outlet end 22 of the Standpipe 20 is arranged at the height of the maximum water level contained in the tank 10 according to its design can in order to obtain a special downward pressure that puts the tank firmly on the seabed, so that the same of the storm effect can certainly resist. A line 23 is used

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det to introduce oil into the storage tank 10 and oil from the same derive. The line 23 is at the same height as the water level when the tank is filled with water, and is therefore at the same level as the overflowing 22 of the standpipe 20. A line 24 is in communication with the inner bottom space of the tank 10 and with a pump 25 which supplies water in pumps the tank when oil is to be drained from it.

FIG. 2 illustrates the construction of the bottom of the tank in more detail than is shown in FIG. A plurality of spaced reinforcement members 31 and 33 are arranged horizontally in order to form a crossing pattern above <fer metal plate 12. The same are held in place by shear connectors 32 ν, which are also attached to the plate 12 until the concrete hardens. Similarly, reinforcement parts 34 are arranged at a distance from one another below the metal plate 13 and reinforcement parts 35 are arranged at a distance from one another to the side of the reinforcement parts 34. Shear connectors 36 hold the reinforcement members in position relative to one another and to the plate 13. The periphery of the concrete ballast I ¹ I is provided with reinforcement parts 37 and 38 which cross each other and which are held at a fixed distance from the vertical jacket 11 by shear connectors 39 which are connected to the jacket 11 until the concrete hardens.

The near-shore storage tank 10 shown in FIGS. 1 and 2 can be built in a dry dock on the coast and then towed to a stand to be scuttled. The sinking of the tank can be effected by pumping sea water into the tank. In the first stages of sinking, the tank can move by 10 incline up to 15 degrees, but will become stable in the upright position when submerged at greater depths.

A tank according to the embodiment of Figures 1 and 2 should have a reasonable net downward pressure by the weight of the material used in the tank plus the concrete ballast I ¹ I to keep the tank securely on the seabed when the tank is in place

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contains at least no more liquid than equal to the pressure which is exerted by a water content in the tank up to the sea water level. However, to the amount of ballast that is used must be reduced to a minimum, it is advisable to always have a liquid content in the tank with a height which is substantially above sea water level so that additional downward pressure is obtained to stabilize the tank. The tank according to Figures 1 and 2 is designed so that it has such a liquid height above sea water level as to provide the additional downward pressure. However, such a liquid level is required for the tank jacket to the. To resist storm influence without collapsing. It therefore appears that such a liquid level should always be maintained in the tank as soon as it is used the same is sunk.

The operation of the tank according to FIGS. 1 and 2 when storing oil is not complicated. When the tank 10 is in place is arranged on the seabed, the water level is raised in the same up to the height of the overflowing 22 of the standpipe 20, in order to fill the tank with oil, oil is passed through the pipe 23 pumped into the tank. Because the oil is less specific Weight than the sea water has, the floating roof 19 will rise and at the same time the interface between the oil will increase and move the water down. The resulting pressure head inside the tank 10 will cause the water to flow out the tank flows through the standpipe 20 and the outlet end 22. With continued pumping of oil into the tank, the interface becomes between oil and water in the tank 10 continue to sink until it reaches the lower end 21 of the standpipe. The tank is then with Oil filled so that the pumping of oil is stopped. The floating roof 19 is moved upwards when the tank is filled with oil until it has reached the upper edge of the vertical cylindrical shell 11 substantially. When the tank is full of oil is filled, the floating roof 19 will be in its uppermost position, indicated at 19A with broken lines

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1st. When the tank is filled with oil, the net pressure of the The oil at the bottom of the tank will be essentially identical to the net pressure obtained when the tank is up to the level of the outlet 22 of the standpipe 20 is filled with water, so that as a result a substantially uniform pressure on the tank bottom whether the liquid in the tank consists of oil, water or two separate layers of the same. A such uniform pressure is calculated to prevent the tank shell from collapsing under the influence of storms.

To drain oil from the tank of Figure 1, a (not shown) Valve in line 23 b are opened and as a result oil will flow out of the same. Water can through the pipe 24 are pumped in by means of the pump 25 in order to press the oil level high enough so that oil is under the action of gravity can flow through line 23.

The tank 40 shown in Fig. 3 is intended for use near the coast for storing oil. The tank 40 has a vertical circular cylindrical shell 4l of metal on, wel rather 42 is attached or connected to the same, having no upper or lower metal plate, although, if desired, one of them or both may be used at its lower end to the concrete ballast plate. The concrete ballast plate 42 has a peripheral edge 50 which extends beyond the shell 41 in order to limit the tilting of the tank under the influence of storms. An enclosure 51 extends from the underside of the ballast plate 42 into the sea bed to prevent the sea bed material below the ballast plate 42 from being eroded.

Stiffening rings 43 are arranged horizontally at a distance from one another on the inside of the vertical jacket 41, around the same against bending by the pressure of sea water and against the forces generated by waves and storms. If desired, the stiffening rings can be on the outside

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of the jacket. A semi-elliptical, arched roof 44 made of metal is supported by the vertical jacket 4l. A ventilation opening 45 in the arched roof 44 enables the air flow in both directions to the emergence to prevent internal pressure different from atmospheric pressure.

The coastal storage tank of Figure 3 can be on the coast in one Dry dock built and then towed to an appropriate stand to be scuttled. Sinking the tank can be accomplished by pumping water inside the tank, taking care when designing the tank that that the weight distribution is uncontrolled tipping and turning prevented. As soon as the tank is partially submerged and the center of gravity is below the center of buoyancy, it is located the tank is in a stable condition and no further setup is required to keep the tank full Stabilize sinking.

The tank of Figure 3 is through the ballast 42, the vertical The shell 41 and roof 44 are weighted enough to provide adequate downward pressure as the tank rises to Sea water level is filled with water sufficient to keep the tank in a stable position on the sea floor. Around .but an additional downward pressure for increased stability obtained, the tank 40 is formed so that it usually contains water up to the line WP and oil up to the line OP, as shown in FIG. The line OP of the oil level and the line WP of the water level are arranged so that substantially the same pressure is exerted on the bottom of the tank when the tank is filled with oil or water to the specified line. The line OP of the oil level is above the line WP of the water level, because oil has a slightly lower specific gravity (about 0.85) than water and therefore a larger oil volume must be stored in the tank in order to obtain a pressure, which is equal to the pressure exerted by a volume of water in the

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Tank with a water level lying on the line WP. Both the OP line of the oil level and the WP line of the water level are arranged above the sea water level, so that under most circumstances a corresponding pressure head is maintained to obtain the desired downward pressure on the tank bottom.

The inlet / outlet line 46 is level with the line WP of the water level arranged. In addition, the outlet 48 of the standpipe 47 is also arranged at the level of the line WP of the water level. The lower end 49 of the standpipe 47 is with the lower Bottom space of the tank in connection. The pump 52 is used to draw water through line 53 into the lower floor space of the tank 40 to pump.

When the tank 40 is not used to store oil, it is kept filled with water up to the line WP of the water level. When the tank is to be used to store oil, oil is pumped in through line 46. As the volume of oil supplied to tank 40 increases, the interface between the oil layer on top of the water continuously decreases and water is forced out through standpipe 47 and outlet 48. Once the interface has lowered the standpipe between oil and water on to the lower end 49, the pumping is terminated by oil in the tank. The oil in the tank will then have reached the line OP of the oil fc level.

When the tank 40 is filled with oil, oil can pass through the line 46 are discharged. As oil is drained through line 46, water is pumped by pump 52 through line 53 into the tank. The pumping of water continues until the water level in the tank reaches the line WP, so that an additional There is downward pressure on the tank bottom due to the height of the water in the tank above the outer sea water level is produced.

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The operation and use of the tank, the means of supplying it of oil in the tank and the device for discharging Water from the tank are designed to have a total liquid content in the tank, which exerts a hydrostatic pressure on the tank bottom per unit area, the is above the external sea water pressure. The result is that the weight of the tank including the ballast always applies a downward pressure which keeps the tank stable under normal seawater conditions. By the inner If the water or oil level is maintained above sea water level, the downward pressure on the bottom will be adequate Stability for the tank jacket, so that it can resist the influence of storms.

EXAMPLE

An offshore storage tank for oil is for the arrangement on the Sea floor formed at a stand which has an average sea water level of 36 m above the sea floor. The tank is circular in horizontal cross-section and has a vertical cylindrical metal jacket that is 52.8 m high and has the general form shown in FIG. A horizontal one Concrete floor slab with a thickness of 1.8 m, which is provided with a metal plate on each side, forms the ballast. On the underside there is an enclosure 16 which penetrates 1.5 m into the sea bed. The tank is with a floating roof provided, within a cylindrical ring 18 with a diameter of 62.4 m and a height of 9.6 m in vertical Direction is shiftable. The tank is designed to accommodate a maximum internal water level of 43.5 m from the sea bed and a maximum inner oil level of 52.2 m from the sea bed educated.

The vertical cylindrical shell 11 consists of twenty-two horizontal rings with a height of 2.4 m, each ring is made of

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Steel plates made. The rings forming the jacket have the following thicknesses from bottom to top: four rings of 18.75mm, four rings of 21.875mm, three rings of 25mm, one 28.125mm ring, one 31.25mm ring, one 34.375mm ring, two 37.5mm rings, one 34.375mm ring, one ring of 28.125mm, one 25mm ring, one 18.75mm ring and two 15.625mm rings. The vertical jacket 11 of the tank is therefore thicker in the area influenced by the wave effect than in the areas below and above.

When the tank is filled with water to the intended height, the tank will have a positive pressure of 9.764 t / dm, and the same pressure should be applied when the tank is filled with oil. The fit of the tank is something more than 119 million liters of oil.

If the tank described is arranged on the sea bed and filled with liquid, no supports are required around the same stable, even with waves 12 m highi that are below Storm influence can arise. The tank has enough dead weight to be stable in storms with a maximum wave height of 4.5 m. The tank can therefore be filled with water until a tanker is being loaded with oil the inner water level-B- at the same level as the outer one Sea water level is located, whereupon additional water can be added to the tank up to the maximum water level 5.7 m above of the sea water level. A height of 14.40 m of the oil (specific gravity 0.85) in the tank gives a positive result Pressure, which corresponds to a height of the water of 5.7 m.

The invention is not limited to the illustrated and described exemplary embodiments, which have various modifications can experience without departing from the scope of the invention.

Claims C 60/47 309834/0344

Claims (14)

Attachment file number for the entry dated December 14, 1972 vA // Name d. Ann «. Chicago Bridge & Iron Company PATENT CLAIMS 1.! Storage tank near the coast, marked by a circular cylindrical vertical jacket and by a continuous horizontal one connected to the jacket rigid bottom, which contains solid ballast and can rest on the seabed, with the vertical coat large enough to hold up when resting of the soil on the ocean floor above the sea water level with eggs to be able to project a height that corresponds to the height of a liquid, which the jacket can contain in the filled state up to a liquid level above the sea water level, in order, together with the pressure of the tank weight, to exert an adequate pressure that the tank under the influence of storms at a stand holds in position on which the tank is to be placed, and whereby the vertical jacket can only withstand the storm influence when supplemented by the internal fluid pressure, without collapsing when the tank rests on the seabed. 2. Coastal storage tank according to claim 1, characterized by a device which supplies a liquid hydrocarbon to _{the tank and discharges the same from the tank 3} and by a device which supplies water to the tank and discharges the same from the tank. 3. Inshore storage tank according to claim 2, characterized in that that the device for supplying a liquid hydrocarbon into the tank and the device for discharging c 6OM7 3098 3A / 03U Water from the tank maintains a total liquid content in the tank that corresponds to the soil per unit area exerts a pressure that is greater than the external seawater pressure. 4. Inshore storage tank according to claim 1, characterized in that that the bottom is provided with a metal plate, on the top of which is a substantially uniform Concrete layer is located. 5. Inshore storage tank according to claim 4, characterized in that that a metal plate is arranged on top of the concrete layer and connected to the vertical casing element. 6. Inshore storage tank according to claim 1, characterized in that that the vertical jacket is made of metal. 7. Inshore storage tank according to claim 1, characterized in that that the vertical jacket is made of concrete. 8. Inshore storage tank according to claim 6, characterized in that that the vertical metal jacket consists of horizontal metal rings and that those subject to the wave action Rings of the jacket are thicker than the other rings of the vertical mfcetallmantle. 9. Inshore storage tank according to claim 6, characterized in that that the vertical metal jacket has a plurality of horizontal, spaced stiffening rings, the connected to the inside of the same. 10. Coastal storage tank according to claim 6, characterized in that that a metal surround extends from the bottom of the tank in a vertical direction downwards. 11. Inshore storage tank according to claim 9, characterized gekennzelch-C 60/47 309834/0344 net that the vertical metal jacket is inside the upper part the same is provided above the adjoining stiffening rings with a ring guiding a cylindrical metal roof, that the ring leading to the cylindrical metal roof has a height. from the maximum water level to the maximum oil level in that Has tank and that a floating roof has a circumference in the immediate vicinity of the inside of the cylindrical metal shell. 12. Inshore storage tank according to claim 2, characterized in that that the device for discharging water from the tank consists of a line inlet which is connected to the lower floor space of the tank is in communication, and that an outlet is arranged at the height of the maximum water level that the tank may contain according to the calculation. 13. Storage tank near the coast according to claim 2, characterized in that that the device for discharging liquid hydrocarbon from the tank consists of a line which has a Has inlet to the tank at the height of the maximum water level that the tank will contain according to the calculation can. c 60/47 309834 / 03U