WO1992009472A1

WO1992009472A1 - Tanker

Info

Publication number: WO1992009472A1
Application number: PCT/EP1991/002235
Authority: WO
Inventors: George Paraskevopoulos
Original assignee: George Paraskevopoulos
Priority date: 1990-11-26
Filing date: 1991-11-26
Publication date: 1992-06-11
Also published as: DE4037577A1

Abstract

The invention concerns a tanker with a number of tanks disposed next to each other in rows parallel to the longitudinal axis of the ship and connected to each other by pipe lines. Some of the tanks lie outboard, while others are inboard, or centreline, tanks. Pumps are fitted to pump the contents of one tank into another and to fill and empty the tanks. The floors (51, 52) of the centreline tanks (5) slope upwards from a central longitudinal bulkhead (50) to a given height which is below the water line (T). The outboard tanks (6, 7) extend in under the centreline tanks (5) and are separated from each other by the longitudinal bulkhead (50). The width of the outboard tanks (6, 7) in the zone extending from the given height to the deck (12) is at least equal to the value required for the distance between the outer hull and the longitudinal bulkhead of double-walled tankers.

Description

Tanker

The invention relates to a tanker of the type mentioned in the preamble of claim 1.

If such tankers are used for the transport of environmentally hazardous substances, such as oil, there is a risk that damage to a side tank or a middle tank caused by material fatigue or by a collision with other ships or obstacles will result in part of the in the cargo transported in the tanks leaks and causes serious environmental damage.

The intention is, for example, to prescribe for tankers for the transport of oil that they must be provided with double side walls and / or bottoms so that no oil leaks out of the tanks in the event of a collision and the resulting damage to the hull. Such tankers with double walls are very expensive both in terms of their construction and in terms of operating costs, additional problems arising from the inaccessibility of the space enclosed by the double walls and raised floors. This applies in particular to raised floors, since there is a risk of oil seeping into the space enclosed by the raised floor and the resulting risk of explosion.

To solve these problems, it is already known

(Literature 'Lloyds List ¹ , Nov. 22, 1990, page 6) to provide a tanker with only double side walls, but not with a double bottom, the amount of oil escaping from a bottom contact being limited by the fact that the ship's hull is limited by a middle deck is divided below the waterline. The one that is affected by ground damage and is below the middle deck Tank is largely protected against the outflow of oil because the pressure of the sea water in this area is greater than the pressure of the oil in this lower tank, so that sea water penetrates into the tank, but no oil escapes. This effect can be improved in that the lower tank is not completely filled, so that an air layer remains between the surface of the oil and the middle deck, which is compressed when sea water enters this tank, so that a larger amount of sea water in the damaged tank can penetrate. However, since the double side walls still extend over the entire height of the ship and have to be at a considerable distance from each other, which is determined by the IMO regulations on the distance between the outer skin and the bulkhead of an outer tank of tankers, a very high result still results large unused space of the tanker, which is undesirable.

The invention has for its object to provide a tanker of the type mentioned, which reduces the volume of the unused space of the tanker with great security in the event of a collision or damage.

This object is achieved by the features specified in the characterizing part of patent claim 1.

Advantageous refinements and developments of the invention result from the subclaims.

The inventive design of the tanker ensures that in the event of a collision and if the outer skin of the ship is damaged, only a very small amount of oil can escape, this amount, according to an older proposal by the same applicant, being able to be further reduced by the fact that the endangered outer tanks have large-volume pipelines are connected to safety tanks under vacuum, with shut-off valves in the pipelines being opened automatically if an external tank is damaged. According to a preferred embodiment of the invention, the bottom walls of the middle tanks also extend obliquely upwards from a central longitudinal bulkhead separating the outer tanks from one another to a predetermined height of the ship, which lies below the lowest water line of the ship that is to be assumed. As a result, the bottom walls of the middle tanks are even better protected against damage when they touch the ground, which mostly occurs to the side of the center line of the ship.

According to a further preferred embodiment of the invention, the outer tanks can be further divided by middle decks in the region of this predetermined height, so that practically none due to the hydrostatic pressure of the sea water

There is a possibility for oil to flow out of the side tanks below the middle decks.

It is possible to leave the area of the outer tanks above the middle decks unfilled, so that these areas form a double-walled area which protects the middle tanks in the event of a side collision.

In this case, according to a preferred embodiment of the invention, it is provided that these upper regions of the outer tanks can be connected to the safety tanks via shut-off valves, pipelines and possibly pumps, in order to prevent the damage from occurring in the event of an extreme damage in which the safety tanks are unable Containing the amount of cargo to be removed, periodically emptying the contents of the safety tanks into these upper areas of the outer tanks, which are not filled during normal operation.

The outer tanks can also be provided with level monitors, which indicate an increase in the level of the oil in these side tanks caused by the penetration of sea water and to trigger the shut-off valves in the safety lines guide that connect the side tanks with the safety tanks. The output signals of the level monitors of the individual tanks can also be sent to a display in the area of the bridge of the ship, so that in the event of a collision it is possible to get a quick overview of the situation that has arisen.

The invention is explained in more detail below with reference to exemplary embodiments shown in the drawing.

The drawing shows:

1 is a schematic cross-sectional view of a conventional tanker,

2 shows a first embodiment of a tanker,

3 is an illustration for explaining the hydrostatic conditions in the tanker of FIG. 2,

4 shows a further embodiment of the tanker,

5 shows a third embodiment of the tanker,

6 is an illustration for explaining the arrangement of safety tanks in the tanker,

7 is a cross-sectional view taken along line A-A of FIG. 6.

1 shows a schematic cross-sectional view of a conventional tanker. This tanker has a bottom 9, side walls 10 and 11 and an upper deck 12. The space delimited by these walls is divided by longitudinal bulkheads 13, 14 into middle tanks 1 and outer tanks 2, 3, both the middle tanks 1 and the outer tanks 2, 3 being divided in length by transverse bulkheads, which means that if the outer skin of the Ship exiting crowd of the charge, hereinafter referred to as simply oil, is reduced as much as possible. Of course, the same considerations and conditions apply to other types of liquid cargo.

The normal water line or diving depth of the ship above the ship's bottom 9 is denoted by T.

In the event of a soil damage 4, the interior of one or more medium tanks 1 of known tankers according to FIG. 1 comes into contact with the surrounding sea water, oil being able to escape from the medium tank until the same pressure prevails on both sides of the damage location 4.

The external pressure is the product of the height T (draft) of the lake water and its density d _sw . The pressure inside the damaged middle tank 1 is similarly the product of the oil level H and the density d _{0 of} the oil. Due to the soil damage 4 oil runs out until

is. Since the density of the sea water d _sw > than the density of the oil d ₀ , H _E > is T, where H _{E is} the pressure equilibrium oil level.

The volume of oil that flows into the sea to achieve this balance is

V _BD = (HH _E ) x W x L,

where B is the width and L is the length of the damaged tank.

The same naturally applies to the damage to one of the outer tanks 2, 3 in the area of its bottom or below the water line. In order to minimize the amount of oil escaping in the event of damage in the area of the bottom 9 of the tanker, it is provided according to a first embodiment of the tanker shown in FIG. 2 that the bottom of the middle tanks 5 does not extend to the bottom of the ship 9, but is arranged at a distance from it so that the side tanks 6, 7 extend below these middle tanks 5 and are separated from one another by a middle longitudinal bulkhead 50.

At the same time, the width of the middle tanks 5 is significantly increased, while the width of the outer tanks 6, 7 is significantly reduced in the area above the waterline and this width corresponds to the width that is specified in the IMO regulations on the distance between the outer skin and the longitudinal bulkhead of an outer tank of tankers is set. As can be seen from FIG. 2, the bottom walls 51, 52 of the middle tanks 5 preferably extend obliquely upwards from the upper edge of the middle longitudinal bulkhead 50 to a predetermined height which is below the diving depth and thus the water line of the ship, this predetermined height is set so that it corresponds to a trough minus a certain tolerance. Above this predetermined height T1, the side walls or longitudinal bulkheads 53, 54, which separate the middle tanks from the outer tanks, extend essentially vertically upwards.

In the embodiment shown in FIG. 2, the amount of oil escaping in the event of soil damage 4 is significantly reduced, since the width of the outer tanks is significantly reduced above the height T1 and in particular above the compensation height H _E.

As will be explained in more detail below, a large part of the volume V _BD is still collected with the help of safety tanks in the event of damage.

The amount of oil that may escape in the event of soil damage can be further reduced as shown in FIG. 3 be that the outer tanks are only loaded up to the height H _s . Since this height is below the compensation height H _E , the pressure of the oil in the interior of the outer tanks 6, 7 is lower, so that 4 water enters the outer tank 7 due to the soil damage, but oil does not escape to the outside.

FIG. 4 shows a further improved embodiment using the same basic ideas outlined above. In this embodiment, the outer tanks 6, 7 are subdivided by a transverse wall or a floor 55 at a height T1, which corresponds to the safety height H _s according to FIG. 3, so that no oil can escape from the side tanks 6, 7 if the floor is damaged. but only sea water enters this side tank 7. The upper side tanks 70 created by the upper floor 55 are still available for the oil transport, but are not protected against lateral collisions. However, the amount of oil which may emerge from the upper outer tanks 70 in the event of a side collision can be kept small by reducing the size of these upper outer tanks by installing transverse bulkheads 61, 71, as will be explained in more detail below with reference to FIG. 6 becomes. Furthermore, the possibility of using safety tanks, which is also explained below, also results in a reduction in the amount of oil that may escape.

If even this small amount of possibly escaping oil cannot be accepted, the embodiment according to FIG. 5 is preferred, in which the space occupied by the upper outer tanks in FIG. 4 is designed as a double-walled ship area 60, 70 with a width that corresponds to the IMO -Determines the distance between the outer skin and longitudinal bulkhead of an outer tank of tankers. If the side wall 10 is damaged below the safety height H _s , no oil can escape from the side tanks 6, 7, since the external pressure of the

Sea water is always greater than the internal pressure of the oil. This is in the right half of FIG. 5 by the pressure lines in Dependence on the height explained in more detail, with the associated heights H _E and T being shown in the left half. T is the normal draft or the diving depth of the ship, while H _{E is} the equilibrium height, that is the height of the oil level that results at the draft T if damage to the hull occurs below this height T. The right half also shows the height T _π i _n , which corresponds, for example, to the minimum draft in the region of a wave trough. The safety height H _s at which the upper floor 55 is arranged is at a height which corresponds to the minimum draft T- _a i _n minus a certain tolerance. The equilibrium height H _e corresponding to a pressure profile P _E, while the safety height H, a pressure profile P _s corresponds to _s. These oil pressures as a function of the height above the bottom wall 9 correspond to an external pressure of the sea water, which results from the pressure _curve P _τ or Ps _άn, that is to say at the minimum diving depth. It can be seen that although the pressure P _E corresponds to the external pressure P, the pressure curve P _{s is} always smaller than the external pressure

P- _r - _a i _n is. There is therefore no risk of oil escaping from the outer tanks 6, 7, and since the area above the safety height H _s , that is to say the double-walled areas 60, 70 are not filled with oil and protect the center tanks 5, there is no overall risk of escaping of oil if the ship is damaged.

Small amounts of oil can be generated from the outer tanks 6, 7 at most by flow movements of the sea water in relation to the ship's hull, and this danger can furthermore be eliminated by part of the amount of oil in a damaged outer tank 6, 7 being explained in the following with reference to FIG. 6 Security tanks is pumped out.

For this purpose, the upper floors 55 of the outer tanks 6, 7 can be connected to upwardly extending shafts or pipes in which level monitors are arranged. at Damage to the hull of the ship below the safety level H _s causes sea water to enter the respective tank for the reasons mentioned above, so that oil is displaced upwards. This is immediately determined by the level monitors 23, which are used to actuate shut-off valves which connect these side tanks to safety tanks, so that at least part of the oil contained in the damaged outer tank is immediately transferred to the safety tanks.

6 shows the arrangement of safety tanks 80, 82 in the tanker. In this embodiment, the safety tanks are separated from the middle tanks 5 by transverse bulkheads 83, 84 and stiffened, so that a high negative pressure can be maintained in these safety tanks 80, 81, which immediately opens the corresponding shut-off valves for transferring the oil from the outer tanks into leads these safety tanks.

In the embodiment according to FIG. 6, the safety tank 80 is connected to the outer tanks 6 and 7 via the pipes 85 and the shut-off valves 91, while the outer tanks 6a and 7a are connected directly to the safety tank 80 via the shut-off valves 92. Furthermore, the safety tank 80 is connected directly to the side tanks 6b and 7b via shut-off valves 93. The safety tank 82 is in direct connection with the side tanks 6c and 7c via the shut-off valves 94 and in connection with the side tanks 6d and 7d via the shut-off valves 95. The two safety tanks are connected to one another via pipes 86 and 87, a shut-off valve 81 being arranged between these pipes.

Furthermore, the safety tanks 80, 82 can each be divided into two chambers by a longitudinal bulkhead. These safety tanks are continuously under vacuum in the manner already mentioned and the shut-off valves and the pipes 85, 86, 87 are dimensioned with a large cross-section, so that the Transfer of the oil from a side tank to the safety tanks can be done very quickly. When the shut-off valves are opened, the pressure difference between the side tank and the respective safety tank creates a very high suction effect, which leads to a rapid emptying of the side tanks, which may be supported by gravity.

The further subdivision by transverse bulkheads 61, 71 is indicated in FIG. 6 with regard to the upper regions 60, 70 of the outer tanks 6, 7. In this way, if the outer wall 10, 11 of an upper area of the outer tank is damaged, the amount of oil that may escape from this area can be reduced

FIG. 7 shows a cross-sectional view along the line A-A according to FIG. 6, the arrangement of the safety tanks in the interior of the outer tanks and the arrangement of the longitudinal bulkheads in the safety tanks being recognizable. Furthermore, this figure shows the arrangement of the upper floors or transverse walls 55, which separate the upper areas 60, 70 from the main part of the outer tanks 6a, 7a. If these upper areas 60, 70 are left unfilled in normal operation so that they form a double-walled protection for the middle tanks 5, it is possible in the event of extreme damage to a large number of tanks to periodically place the contents of the safety tanks 80, 82 in these upper areas 60.79 to drain if the safety tanks cannot hold the amount of oil to be removed from the damaged tanks. In this case too, the safety tanks 80, 82 are connected to the upper regions 60, 70 via pipelines, shut-off valves and possibly pumps.

Claims

1. tanker with a number of tanks, which are arranged in rows next to each other parallel to the longitudinal axis of the ship and connected to one another via pipelines, some of the tanks forming outer tanks and another part inner tanks, and pumping means for pumping the contents of a tank for another and for filling and emptying the tanks, characterized in that the bottom walls (51, 52) of the middle tanks (5) starting from a middle longitudinal bulkhead (50) diagonally upwards to a predetermined height below the Diving depth (T) of the ship, extend, and that the outer outer tanks (6,7) extend to below the middle tanks (5) and are separated from each other below the middle tanks (5) by the longitudinal bulkhead (50), the width the outer tanks (6,7) in an area that extends from the predetermined height to the ship deck (12) mi at least corresponds to the value prescribed for the distance between the outer skin and the bulkhead of double-walled tankers.

2. Tanker according to claim 1, characterized in that the outer tanks (6, 7) are divided in the predetermined height by an intermediate deck (55) in the vertical direction into a lower main part and upper areas (60, 70),

3. Tanker according to claim 1, characterized in that an intermediate deck (55) at the predetermined height separates the side tanks (6,7) from a double-walled side wall region (60,70) of the tanker, through the outer wall (10,11) and a longitudinal bulkhead is formed which forms the outer wall (53) of the middle tanks (5).

4. Tanker according to one of claims 2 or 3, characterized in that the intermediate deck (55) has openings which open into a shaft or a tube (22) which extends vertically upwards and are arranged in the level monitor (23) .

5. Tanker according to one of the preceding claims, characterized in that a part of the middle tanks (5) or partial areas thereof are designed as a safety tank (80, 82) which are continuously subjected to negative pressure and via shut-off valves with the outer tanks (6, 7). stay in contact.

6. Tanker according to claim 5, characterized in that the safety tanks (80, 82) are connected to the interior of the double-walled side wall areas (60, 70) via shut-off valves, pipelines and / or pumps, which in the event of damage involve transferring the contents of the safety tanks allow in the side wall areas.