JPS59429B2 - Liquid storage tank that uses sub-tanks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for storing a water-insoluble liquid such as raw heavy oil in a storage tank, and particularly to a method of this type that utilizes a sub-tank.

Various types of water-insoluble liquids, including raw oil and heavy oil, are normally stored in various underground storage tanks, but recently they have been stored in the sea or in landfills near the coast, using the difference in specific gravity with seawater to move them downward into the storage tanks. A method and apparatus have been developed for introducing seawater and storing a storage liquid having a specific gravity lower than that of seawater by floating it on the seawater in a storage tank (for example, Japanese Patent Publication No. 47-9192 or Japanese Patent Publication No. 47-2476).

The present invention utilizes the advantages of containment and storage that utilizes this difference in specific gravity, and maintains the liquid surface position, that is, the level of the pontoon roof, approximately constant regardless of the amount of stored liquid.
This paper relates to a method for storing non-aqueous liquids using a sub-tank for liquid level control.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to preferred embodiments illustrated in the accompanying drawings.

The underground floating loop type cylindrical storage tank 1 shown in the drawing (only a part of which is shown in cross section) has replacement water 1 in its lower part.
3 is provided with an opening or a through hole 2 through which it can communicate with the outside.

A sub-tank 3 for liquid level control is buried or installed adjacent to the storage tank 1 with its upper edge at approximately the same level, and a hydraulic communication pipe is connected between the sub-tank 3 and the through hole 2. Connect 4. The liquid level control sub-tank 3 is equipped with a water supply and drainage system consisting of a pump 5, piping 6, a valve 11, and a piping 14 for discharging and inputting nearby seawater or industrial water, etc., and for raising and lowering the water surface of the sub-tank. The pontoon roof T of the storage tank 1 has a storage liquid receiving and discharging nozzle 8, and a pipe 9
A receiving and dispensing pump 10 is installed.

In order to store liquid in such a storage tank, first, as shown in FIG. 2, seawater or industrial water (hereinafter referred to as water) is used.

) is injected into the sub-tank 3 from the pump 5 and allowed to flow from the sub-tank 3 through the hydraulic communication pipe 4 until the storage tank 1 is full, that is, until the pontoon roof T reaches a predetermined level. The liquid level in the storage tank 1 and the liquid level in the sub-tank 3 are substantially the same. That is, the height H1 of water from the through hole 2 of the storage tank 1 to its liquid level matches the height HOl from this through hole 2 to the liquid level of the sub tank 3. Into the storage tank 1 in this state, a liquid with a light specific gravity to be stored, such as raw heavy oil whose fluidity has been increased by heating, is introduced into the upper part of the storage tank through the pipe 9.

Due to this introduction, the height of the liquid level in the storage tank 1, that is, the height position of the pontoon roof 7 tends to rise. At this time, the displacement of the pontoon roof from the set position is detected, and when the displacement is detected, the water head pressure is adjusted by varying the amount of water discharged from the sub tank 3 through the valve 11 and piping 14, As a result, the liquid level in the storage tank 1, that is, the height of the bontoon roof 7 is kept substantially constant. FIG. 1 shows a state in which only H2 of raw heavy oil is introduced in this way, and water becomes H3.

Since the specific gravity of raw heavy oil is lighter than water, the liquid level height in sub tank 7 at this time is H. becomes. This relationship is expressed as follows.

HOXdlXtl=H2×D2×T2+H3×D,×t
(Here, d1 is the specific gravity of water, D2 is the specific gravity of crude oil, T,,
t:, T2 indicates a correction value based on temperature.

The raw heavy oil thus stored and stored is discharged through the nozzle 8 and piping 9 by the receiving and discharging pump 10.

In this case, as mentioned above, if the displacement of the bontoon roof 7 from the level setting position is detected, the water head pressure is adjusted by varying the water volume of the sub tank 3 using the piping 6 and the pump 5. The level of the ribbon tone roof 7 is maintained substantially constant. As a result, the vertical movement of the pontoon roof is always kept at a constant position within the range of slight vertical movement.

According to this method, since a sub-tank is involved, even when seawater is used, it is not affected by changes in sea level or other sea conditions. The explanation so far has been based on an underground storage tank, but the same can be said for an above-ground storage tank by installing the sub-tank for liquid level control on a pedestal, etc., so that it is near the upper edge of the tank. can achieve the purpose.

As described above, the present invention detects the position of the pontoon roof of a floating roof storage structure, and controls and interlocks the amount of replacement water in the storage tank with the liquid level of the sub-tank connected to the storage tank so that the pontoon roof of the floating roof storage structure is at a predetermined position. It is characterized by

In other words, raw heavy oil, etc., which is lighter than water, is stored in the storage tank, and the bontoon roof fluctuates depending on the difference in the depth of the stored liquid and the specific gravity of the water. It is a position. Conventional technology (Tokuko Showa 4
7-9192) in this point. That is, in the prior art, it is necessary to keep the regulating liquid level higher than the height of the tank roof, but in the present invention, the liquid level in the sub-tank is, on the contrary, lower than the liquid level in the storage tank. In addition, the prior art described in the above-mentioned publication proposes to always apply water pressure to the dome-shaped roof to prevent the generation of gas, but even if some liquid pressure is applied to the roof, the roof If the area is large, the hydraulic pressure will be enormous. Since the present invention has a structure in which the liquid level is set approximately constant,
A lightweight single deck or double deck structure can accomplish this purpose. In addition, in the case of a general floating roof structure, since it moves up and down, when the floating roof lowers, not only the oil adhering to the inner wall of the tank is vaporized, resulting in a lot of loss, but also vaporized gas accumulates on the side walls of the storage tank and the top of the floating roof. According to the present invention, the floating roof is maintained at a constant height, so this problem is totally solved.

[Brief explanation of drawings]

Fig. 1 is a road surface vertical cross-sectional view of an underground pontoon roof type storage tank using a sub-tank for liquid level control according to the present invention;
The figure is a similar diagram showing a situation in which only replacement water is filled, such as at the start of storage or when the stored liquid is completely discharged. 1...Cylindrical storage tank, 2...Through hole, 3.
...Liquid level control sub-tank, 4...Water pressure communication pipe, 5...Pump, 6...Piping,
7...Storage tank bontoon roof, 8...
Storage storage liquid receiving and dispensing nozzle, 9...Piping, 1
0...Pump for receiving and discharging, 11...Valve, 12...Storage and storage liquid, 13...Displacement water, 14...Piping .

Claims (1)

[Claims] 1. A sub-tank for liquid level control, which has an opening penetrating the tank wall at the bottom of a storage tank for storing a non-aqueous liquid lighter than water, and is installed on the upper edge of the storage tank with its upper edge substantially at the same level; and the storage tank. A water-insoluble substance lighter than water that is connected to the bottom opening by piping, leads seawater or water from the sub-tank to the lower part of the storage tank, and balances the head pressure due to the water level of the seawater or water in the sub-tank and the bottom pressure inside the storage tank. In a method for storing and storing a liquid, displacement from a set position of a pontoon roof is detected when discharging and receiving non-aqueous liquid from the storage tank, and when the displacement is detected, a water supply and drainage connecting the sub-tank and a water source are detected. Storing and storing a non-aqueous liquid lighter than water, characterized in that the water head pressure is adjusted by varying the water volume in the sub-tank using a device, thereby keeping the liquid level in the storage tank substantially constant. Method.