DE2534832A1 - DEVICE FOR STORAGE TANKS CARRIED ON THE GROUND, IN PARTICULAR FOR OIL STORAGE TANKS TO AVOID GROUNDWATER POLLUTION - Google Patents

Description

PATENT ADVOCATE DIPL.-PHYS. HEINRICH SEIDS

62 Wiesbaden · Bierstadter Höhe 15 · P.O. Box 12068 · Telephone (0 6121) 56 53 82 Postsdiedc Frankfurt / Main 1810 08-602 · Bank Deutsche Bank 395 63 72 · Nass. Sparkasse 108 00 30 65

Wiesbaden, the 3Λ. July 197-5 A 161 S / rd

Lars Jörgen ANDERSEN DK-2860 S ^ nborg - Denmark

Device for storage tanks carried on the ground, in particular for oil storage tanks for Avoidance of groundwater pollution

Priority: Danish patent application No. 43.68 / 74 of August 15, 1974

The invention relates to a device in connection with storage tanks carried on the ground, in particular oil storage tanks, to avoid groundwater contamination from leaking Tank contents, whereby a storage tank or a number of storage tanks are replaced by a substantially vertical, impermeable, encircling partition wall reaching into the ground.

The object of the invention is to provide a device as specified above Creation of a way that reduces the risk of groundwater contamination by leaking tank contents by means of simple

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and. reliable furniture parts practically complete is excluded.

This object is achieved according to the invention in that the partition is made airtight and connected in an airtight manner to an upper screen, which is preferably through the tank bottom can be formed, and that a vacuum pump is arranged for this purpose, continuously or intermittently To generate vacuum in the porous floor containing and delimited with the partition wall space.

In this way it is possible to maintain a vacuum in the space containing the porous bottom and bounded by the surrounding partition wall, and it is possible to draw off the liquid in this bottom space by suction, so that any presence of substance stored in the container, preferably oil , can be determined. (In the following, for the sake of clarity, the term "oil is used for any substance stored in the tank".) By switching on the ^; Air and then water can be withdrawn from the vacuum pump, after which the water is checked for oil content. If the water does not contain any oil, the vacuum pump can be stopped, whereby the vacuum due to the inevitable leaks all j

is gradually lost. But when the water stops, it is

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DJpL Phys. Heinrich Seids · Patent Attorney · 62 Wiesbaden · Bierstadter Höhe 15 · P.O. Box 120 68 · ® (0 6121) 56 5382

_3_ 2§34832

it is possible to continuously withdraw the mixture of water and oil via the suction line, after which the mixture of oil and Water is either introduced into the storage tank (applies to other substances stored in the tank as far as this allows) or subjected to a separation process to separate the oil from the water.

A simple way of separating the oil from the water can be achieved by means of a suction line that extends from the extends upper part of the porous floor containing space and contains a vacuum container, at the upper part of which Vacuum pump is connected to draw off air. Any in the floor space delimited by the partition wall Oil therefore collects on the surface of the liquid in this vacuum container, and can then be removed from this surface withdrawn by means of a special pump and then returned to the storage tank itself. The liquid level in the vacuum container can be indicated by means of a conventional water level tube, and also gives a direct indication for the condition of the storage tank in the floor space prevailing vacuum. By letting atmospheric air into the vacuum container, it is possible to keep the pure water in the Return the bottom part of the vacuum container under the storage tank. After a certain period of time you can use the vacuum container

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Dipl.-Phys. Heinrich Seids · Patent Attorney · 62 Wiesbaden · Bierstadter Höhe 15 · Postfadi 120 68 · ® (0 6121) 5653

fill up again by suction. In this way then the meanwhile on the surface of the groundwater within The oil collected by the partition is drawn into the vacuum container. In this way, a special separation container is created for the Avoid mixing oil and water.

A better insight into the processes taking place in the device can be achieved if in a further development of the invention the vacuum container is completely or partially transparent. This way, the level of oil contamination can be reduced can be observed directly in the withdrawn groundwater.

A considerable increase in the efficiency or increase in the oil content in the extracted groundwater is achieved, if, within the scope of the invention, the upper screen is concave on its underside, and the suction line is on a place near the highest lying area. of the screen opens. When the groundwater with the oil up its surface in the cavity within the surrounding partition wall increases (under the effect of the applied vacuum), the horizontal cross-sectional area decreases with increasing level, so that the thickness of the oil layer increases accordingly. In this way it is possible to draw almost pure oil into the vacuum container, and so during the separation of oil time

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to save. This also makes it possible to have both vacuum vessels and vacuum pumps with considerably smaller capacity to choose. The extent of the concave design of the upper screen can, for example, be such that the upward curvature is about 30 per mil from the peripheral edge to the center of the screen.

In order to reduce the flow resistance against the extraction of oil from the floor cavity, within the scope of the invention a layer of well-permeable material can be attached immediately below the upper screen, for example Gravel or coarse gravel. This causes a considerable reduction in the flow resistance for the oil or the oil water contaminated with oil. The peeling process is considerably shortened compared to simple soil or sludge would be arranged under the upper screen.

In a further development of the invention, it is possible to accelerate the removal of oil by a considerable amount if a A plurality of air valves for admitting "secondary air" from the atmosphere is distributed around the circumference of the partition wall. ; As was found in the conduct of experiments, the air bubbles brought into the oil in this way contribute greatly to this

■ - - i

in order to detach the oil particles from the particles of the well-permeable material, so that the flow resistance for the oil

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continues to decrease. The removal of the oil is therefore even faster, which in terms of the intake of "secondary air" would not be expected at first.

It is possible, using simple pieces of equipment, to determine in which surface area a leakage may have taken place, in which, as a further development of the invention, each of the air valves is connected to a perforated air inlet duct which extends along a part of the circumference of the surrounding partition wall, namely at the inside of this partition wall, the holes in this air duct preferably being directed towards the open end of the suction duct. By opening only one air valve in a period of time and observing the mixture drawn into the vacuum container, it is possible, in the event of a leak, to determine in which sector of the tank bottom this leak is located. The tank bottom may for example be divided into sectors of sechaehn ie 22.5 °.

In the context of the invention, the entire device can be set up for automatic operation in a simple manner by the vacuum container has a device for monitoring the standing height and for switching on and stopping the vacuum pump Minimum standing height or maximum standing height and the suction line from

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the floor space towards the vacuum container and the vacuum pump to the outside atmosphere get a check valve, which to do this is formed, the liquid in its closed position slowly flow back from the vacuum container in the floor space bounded by the partition. In such case it works the device in such a way that the vacuum container is initially filled up to the maximum level by suction, after which the vacuum pump is stopped. The oil now collects on the surface of the liquid in the vacuum container, while the liquid level slowly reaches the minimum level drops, and practically pure water flows back from the lower part of the vacuum container into the floor space. Simultaneously the oil is drawn off from the surface of the liquid in the vacuum container by suction. When the liquid level has dropped to the minimum level in the Vpküumpump, the Vpküumpump is switched on again, and the operation repeats itself automatically.

The invention is to be explained in more detail below using an exemplary embodiment with reference to the drawing. Show it:

Fig. 1 is a diagrammatic and greatly simplified representation of a storage tank for oil, the

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Dipl.-Phys. Heinridi Seids patent attorney 62 Wiesbaden Bierstadter Höhe 15 Postfadi 120 68 ® (0 6121) 56 53 82

with a device according to the invention

is equipped;
Fig. 2 is a vertical section through the bottom of the

Tanks in the middle bottom area; 3 shows a diagrammatic vertical section through

a vacuum container and FIG. 4 shows a vertical section of the side wall and bottom

of the tank at the circumference.

In the example shown is a large cylindrical oil storage tank 1 carried on the ground, the height of the ground being indicated at 2 and the water table at 3. the The side wall of the tank 1 rests on an annular partition 4, which protrudes from a slightly above the floor level Height extends a little below the water table 3 reaching depth.

In the example shown, the Tpnkboden 5 is on the underside concave and contains a centrally arranged, upwardly extending sump 6. A suction head 7 is located in the sump 6 arranged, the one extending in the ground below the tank bottom 5 through the partition 4 to the outside

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Suction line 8 is connected. Outside the partition 4, the suction line 8 opens into the bottom of a vacuum container 9, the upper part is connected to the suction side of a vacuum pump 10.

Figure 2 shows the sump 6 and the suction head 7 on a larger scale. Below the tank bottom 5 there is one Asphalt layer 11 and under this layer 11 a gravel-asphalt-concrete layer 12. Under this gravel-asphalt-concrete layer 12, a layer 13 is arranged which is designed for this purpose is when creating or pouring the gravel-asphalt-concrete material to prevent penetration into the underlying layers. Under the layer 13 is located a rather thick layer of gravel or river gravel in order to attract the flow resistance for that which is to be drawn through the suction head 7 Reduce oil-water mixture. At a certain distance below of the suction head 7, a horizontal, oil-proof concrete lens 14 is arranged to prevent water or oil flowing through the suction line 8 flows back, preventing it from going too deep into the soil layer under the tank due to the inherent kinetic energy penetrate the liquid. Conventional foundation materials are located beneath the layer of crushed stone or river gravel, like sand or gravel.

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Dipl.-Phys. Heinrich Seids · Patent Attorney · 62 Wiesbaden · Bierstadter Höhe 15 · P.O. Box 12068 · ® (0 6121) 56 53

FIG. 3 shows in diagram form the most important structural features of a vacuum container 9 to be used in accordance with the invention . In Figure 3, the current level is shown as lying approximately in the middle between the two extreme levels, and an oil layer 19 can be seen on the surface of the liquid. This oil layer 19 can be drawn off by means of a flexible hose 20 which is connected to a float 21 floating on the surface of the oil layer 19. The hose 20 extends out on the vacuum container 9 and is connected to the suction side of a pump 22 which pumps the oil back into the storage tank 1 check valve 23 is fully open, when the vacuum pump draws air from the vacuum containers 10 9 while it is partially closed \, when the vacuum pump is at rest. In this way, the check valve 23 allows the air to flow slowly

flows in the direction indicated by the arrow. Further there is a shut-off valve 24 in the line between the vacuum container 9 and the vacuum pump 10. On the top of the vacuum container 9 there is another : shut-off valve 25 for rapid admission of air into the

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Vacuum container. When the vacuum pump 10 is at a standstill, air slowly flows into the vacuum container 9 through the partial closed check valve 23 back so that the liquid level drops to the lower level 15, During this Process practically pure water flows through the suction line 8 back into the floor space within the partition wall 4. If the liquid level has dropped to the lower level 15, the vacuum pump 10 is started and pulls right quickly again up the liquid to the upper level 16, after which the vacuum pump is stopped again. If now the liquid slowly sinks to the level 15, the oil layer 19 collects on the liquid surface, from where it is continuously or intermittently withdrawn through the hose. If the fluid level then again This process is repeated until the mirror 15 has sunk.

FIG. 4 shows an air valve 26 for admitting atmospheric air into the floor space within the partition wall 4. On the inside the dividing wall 4, the line coming from the air inlet valve 26 opens into a line or a pipe 27 which extends extends along the inside of the partition 4 on both sides at equal distances from the valve 26. The pipe 27 has a Row from horizontally to the center of the tank bottom 5 »i.e.

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after the suction head 7 directed holes. When the air inlet valve 26 is completely or partially open, "secondary air" is drawn into the floor space within the partition 4, so that air bubbles penetrate the oil-water mixture. It has been found that these air bubbles contribute considerably to The oil from the stones is able to peel off gravel or river gravel.

The device includes sixteen air inlet valves 26 with associated pipes 27, each over an angular range of 22.5 ° of the tank circumference. If only one at a time of the valves 26 is opened within a period of time, it is possible by observing the withdrawn mixture in the fully or partially transparent vacuum container 9 to determine whether any oil in the corresponding sector of the floor space has flowed out. In this way it is possible to prevent any leaks in the Locate the bottom of the tank.

Leaks in the tank bottom, the oil in the porous material The space contained under the tank can escape very quickly, easily and safely by locking the Oil smells can be detected in the air pumped out during evacuation.

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If for any constructional reasons it is desired or necessary to design the tank bottom 5 with a convex underside, A layer of material, which forms a screen for the partition wall 4 which is concave downwards, can be arranged under the tank bottom 5 will. However, this additional material layer can also be omitted if instead of the device shown the removal is carried out on the circumferential area of the tank bottom, which would then be considerably higher than the central part of the tank bottom. Such an arrangement, however, would require the use of a plurality of suction heads 7 instead of just require a single one.

-Patent claims-

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Claims (8)

Dipl.-Phys. Heinrich Seids · Patent Attorney · 62 Wiesbaden · Bierstadter Höhe 15 · Postfach 120 68 · ® (0 6121) 56 53 - 14 claims 1) ^ facilities for storage tanks carried on the ground, in particular oil storage tanks, to avoid groundwater contamination from leaking tank contents, wherein a storage tank or a number of storage tanks by a substantially vertical, impermeable, in the partition gripping the floor is surrounded, characterized in that the partition (4) is airtight and connected in an airtight manner to an upper screen (5, 13), which is preferably through the tank bottom (5) can be formed, and that a vacuum pump (10) is arranged for this purpose, continuously or intermittently to generate a vacuum in the porous floor containing and with the partition wall (4) delimited space. 2) Device according to claim 1, characterized in that that the suction line (8) extending from the upper area of the porous base is a vacuum vessel (9), to the upper part of which the vacuum pump (10) is connected. / 15 609809/0371 Dipl.-Phys. Heinrich Seids · Patent Attorney · 62 Wiesbaden · Bierstadter Höhe 15 · P.O. Box 12068 · ® (0 6121) 56 5382 3) device according to claim 2, characterized in that that the vacuum vessel (9) is completely or partially transparent. 4) Device according to claim 1, characterized in that the upper, with the upper part of the surrounding partition wall (4) connected screen (5, 13) is concave on the underside, and that the suction line (8) on a
Place next to the highest part
this screen (5, 13) opens. 5) Device according to claim 4, characterized in that that a layer of well-permeable material, for example gravel, river gravel or coarse gravel immediately is arranged under the upper screen (5, 13). 6) Device according to claim 4, characterized in that that a plurality of air valves (26) for admitting "secondary air" from the atmosphere around the perimeter of the surrounding partition 4 are arranged distributed. / 16 6098 09/037 1 Dipl.-Phys. Heinrich Seids · Patent Attorney · 62 Wiesbaden · Bierstadter Höhe 15 · P.O. Box 120 68 · ® "(0 6121) 56 53 7) device according to claim 6, characterized in that that each of these air inlet valves (26) with a perforated line piece, for example pipe (27) is connected, which extends along part of the circumference of the surrounding partition (4) on the inside this wall extends, the holes of this line piece or pipe (27) preferably on the open End (7) of Sugleitung (8) are directed. 8) Device according to claim 2, characterized in that the vacuum container (9) has a device (17 »18) for level control for switching the Vacuum pump (10) at a lower liquid level (15) or a higher liquid level (16) around the suction line from the floor space via the vacuum container (9) and the vacuum pump (10) to atmosphere contain a check valve (26) which is designed to be in its closed position of the liquid a slow To allow backflow from the vacuum container (9) to the floor space within the surrounding partition (4). 60981) 9/0 371