JPS6222674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a water storage tank that separates and recovers oil dispersed in water by flotation.

Water containing dispersed oil, such as ballast water discharged from the ballast tanks of petroleum tankers, is temporarily stored in a tank and separated and collected after waiting for the oil to rise to the surface due to the difference in specific gravity. . As a device used for this purpose, the present inventor previously proposed a water storage tank with an opening in the center of a floating roof and an oil extractor attached to the lower surface of the opening slanted upward toward the center. 55-19642). Next, in order to reduce the weight of floating roofs, a flat plate shape was used, a cylindrical partition wall extending downward was installed at the opening, and a water tank with a floating oil separation device using an oil extractor was disclosed (Japanese Patent Application Laid-Open No. 55-48083).

In the case where a cylindrical partition wall is provided at the opening of a flat floating roof, this partition wall and the flat plate of the floating roof form a closed space at the top together with the side wall of the tank, and this serves as an oil storage area. It is. As shown in Figure 1, when the amount of oil separated from water and stored exceeds the lower end of the partition wall, that part overflows and collects in the opening, and is recovered by opening the valve connected to the oil extractor. Based on.

Although this water storage tank with a floating oil separator had some effects, the improvement of the one proposed this time is that the recovered oil can be concentrated to a higher degree.

The inventors of the present invention have investigated in detail the behavior of oil and water in the oil storage area of the above-mentioned apparatus, and have found that even if an oil-water interface is formed, the inside of the oil phase is not uniform. That is, as schematically shown in Fig. 2, the oil phase, from the upper layer to the lower layer, roughly consists of... concentrated oil layer... mixed layer of emulsionized oil and sludge... emulsionized sludge layer... The emulsion is composed of layers that can be divided into sludge layers (of course, there are no clear interfaces between the layers), and as time passes, the emulsion gradually breaks down and turns into a concentrated oil.
In other words, it was found that the oil storage area serves as an oil concentration area.

Based on this knowledge, the present inventor has determined that in the separation and recovery of floating oil, the uppermost layer of the above oil phase ()
If the concentrated oil layer is removed, oil with minimal sludge components and water content can be recovered, and subsequent storage will break the emulsion layer and regenerate the concentrated oil layer. We came to the conclusion that we should start from the top, not the bottom.

The present invention embodies this conclusion and aims to provide a water storage tank with a floating oil separation device capable of recovering the most highly concentrated oil. This results in
Subsequent disposal of the recovered oil is significantly easier than with conventional water storage tanks.

In the water storage tank with a floating oil separator of the present invention, a flat floating roof with an opening in the center is installed in the tank, and the opening of the floating roof has a cylindrical partition wall extending downward. In a water storage tank equipped with a floating oil separator, which forms a floating oil concentration area together with the flat plate of the tank and the side wall of the tank, and an oil collector is installed in the opening to collect the oil that overflows from this area, the upper part of the floating oil concentration area and The present invention is characterized in that a downward passage for concentrated oil is provided, which communicates with the partition wall and opens at an upper portion than a lower end of the partition wall.

As an example, an oil/water separation mechanism and an oil recovery operation will be described with reference to the drawings.

When a predetermined amount of ballast water 10 is introduced into the water storage tank 1 and left to stand still, oil floats to the surface due to the difference in specific gravity, and an oil phase 12 is formed on top of the water phase 11 under the floating roof 2. The oil-water interface A gradually decreases as the oil phase 12 increases, and reaches near the lower end 31 of the cylindrical partition wall 3 provided at the opening of the floating roof. During this time, the formation of each layer in the oil phase described above and the breakage of the emulsion progresses, resulting in a change to a concentrated oil content. When the amount of oil phase exceeds a certain limit, the uppermost layer, that is () in Figure 2,
A part of the concentrated oil layer is transferred to the free water surface of the opening of the floating roof through a concentrated oil passage, which is a pipe 4A that is provided in the partition wall 3 so as to communicate with the inside thereof and opens upward from the lower end 31 of the partition wall. It emerges to the top, where it also forms an oil phase 13. This oil is taken in from the oil inlet 61 by passing through the swing pipe 7 and opening the valve 8 connected to the oil extractor 6.

The oil extractor 6 is integrally attached to the floating roof 2 using a fitting 62. Therefore, as the floating roof rises and falls,
The oil extractor 6 also moves within the water storage tank 1. Note that it is preferable that the position can be changed slightly by the adjustment means 63. These matters are the same as those disclosed regarding the previous invention.

In the water storage tank with a floating oil separator of the present invention, the length of the pipe 4A is made smaller than the depth of the cylindrical partition wall 3 because it is tangled so that concentrated oil can be pushed out through the pipe. The principle will now be explained using FIG. The pressure acting on the interface A between the oil phase 12 in the oil concentration zone and the water phase 11 below it is ・H ₁ , assuming the average specific gravity of the oil phase, while on the other hand, the pressure acting on the oil-water interface B at the opening of the pipe is The working pressure is ρo ₁ ·H ₂ , assuming that the specific gravity of the concentrated oil is ρo ₁ . When the pressures inside and outside of the cylindrical partition wall are balanced at the depth of the oil-water interface A, the following equation holds true, if the specific gravity of water is expressed by ρw: ・H ₁ =ρo ₁・H ₂ +ρw・ΔH. If we subtract ρw·ΔH from the right side of the above equation, we get ・H ₁ >ρo ₁・H ₂ . Therefore, the force (・H ₁ −ρo ₁・H ₂ ) is applied to the pipe 4A.
It acts downward on the oil at the lower end 41 of the holder, causing the oil to flow out. And the oil content flowing out from the bottom end of this pipe is ・H ₁ =ρo ₁・
Continues until _H2 .

The passage for concentrated oil has the same function as the above-mentioned pipe, as long as it communicates with the concentration area inside the cylindrical bulkhead and opens above the lower end of the bulkhead, and there are no restrictions on the shape. There isn't.
As another aspect, the configuration shown in FIG. 5 is recommended. This is because a passage for concentrated oil is provided concentrically on the cylindrical partition wall 3 forming the floating oil concentration area and on its inner side (near the center), connected to the floating roof flat plate 2, and directed downward, and is directed downward from the bottom end of the partition wall. It takes the form of a cylindrical space 4B, which is formed by another cylindrical partition terminating above 31 and communicates with the concentration zone.

The one in which a plurality of pipes 4A are provided as described above is useful as a modification measure for an existing actual device that embodies the previous invention, while the latter one that utilizes the space 4B formed by the double cylindrical partition wall is suitable for newly installed equipment. suitable for

[Brief explanation of the drawing]

FIG. 1 is for explaining a water storage tank with a floating oil separator proposed earlier by the present inventor.
A is an overall sectional view, and B is an enlarged sectional view of main parts. FIG. 2 is a schematic cross-sectional view showing the composition of the oil phase in the oil storage area of the water tank shown in FIG. 1. FIG. 3 is for showing an example of the present invention, and shows the main parts of a water storage tank equipped with a floating oil separator.
FIG. 1B is an enlarged sectional view corresponding to FIG. 1B. FIG. 4 is a diagram for discussing the relationship of dimensions of each part in the example of FIG. 4. FIG. 5 is a sectional view corresponding to a part of FIG. 3 to show another example of the present invention. DESCRIPTION OF SYMBOLS 1... Water tank, 2... Floating roof, 3... Cylindrical partition, 4A, 4B... Concentrated oil passage, 6... Oil extractor, 11... Water phase, 12... Oil phase.

Claims (1)

[Scope of Claims] 1. A flat plate-shaped floating roof with an opening in the center is installed in the tank, and a cylindrical partition wall extending downward is provided at the opening of the floating roof, so that the flat plate of the floating roof and the tank are In a water storage tank equipped with a floating oil separation device, which forms a floating oil concentration area together with the side wall, and has an oil collector installed in the opening to collect oil that overflows from this area,
A water storage tank characterized in that a downward concentrated oil passage is provided which communicates with the upper part of the floating oil concentration area and opens above the lower end of the partition wall. 2. A water storage tank with a floating oil separator according to claim 1, wherein the passage for concentrated oil is a plurality of pipes that communicate with the inside of the partition wall and are provided downward from the top of the partition wall. 3. A channel for concentrated oil is provided in a cylindrical bulkhead forming a floating oil condensing area and concentrically inside the cylindrical bulkhead, connected to the floating roof plate, facing downward, and terminating above the lower end of the bulkhead. A water storage tank with a floating oil separation device according to claim 1, which is a cylindrical space formed by a partition wall and communicating with a concentration zone.