JPS6152065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-hull type water-encased oil storage tank in which an inner tank for storing oil floating on water is surrounded by water in an outer tank.

Conventional cylindrical tanks for storing petroleum are classified by roof type into fixed roof type and floating roof type, but these two types of tanks each have the following problems.

1.Fixed roof type (1) A ventilation valve is installed on the roof, which allows oil to be taken in and taken out and breathes due to changes in outside temperature, resulting in large vapor loss from stored oil. Also, pollution is caused by vapor emissions.

(2) When discharging oil, vapor gas may mix with the atmosphere that entered through the vent valve, causing explosive gas to fill the tank, which is dangerous.

(3) In general, the construction cost of a fixed roof is relatively high, and the assembly period is relatively long. For this reason, it is not used in large tanks.

2. Floating roof type Although this type has improved the various drawbacks of the fixed roof type mentioned above, it still has the following problems.

(1) There is a problem with the structural mechanism of the weather hood that prevents rainwater from entering between the outer periphery of the floating roof and the tank side plate, and many efforts have been made to solve this problem, but there is no technology that completely prevents rainwater from entering. has not been established.

(2) The sealing mechanism between the tank side plate and the pontoon also has the same problem as (1) above.

(3) Although the risk of fire is lower than that of a fixed type, there is still the problem of so-called rim fire between the pontoon and the side plate.

(4) Although vapor loss is significantly improved compared to the fixed type, work loss occurs due to evaporation of oil adhering to the side panels when the floating roof is raised and lowered.

Furthermore, problems common to both types include corrosion of the bottom plate, damage near the annular plate due to uneven ground subsidence or earthquakes, oil leakage out of the tank due to sloshing during earthquakes, and fires caused by this. There is a problem.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a double-hull water storage tank that eliminates vapor loss and improves fire resistance, earthquake resistance, and weather resistance. This is what I am trying to do.

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is an open top outer tank consisting of a bottom plate 2 and side plates 3, and is installed on a foundation mound 4.
The bottom plate 2 is sloped downward toward the center. 5 is a water supply pipe connected to the center of the bottom plate 2;
Water W is supplied from the water storage tank 6 by a pump 7, and is also used as a drain pipe when cleaning the inside of the tank 1. Reference numeral 8 denotes a baffle plate provided opposite to the opening of the water supply pipe 5 in the tank 1, and serves to direct the pumped water W laterally so that it does not spout directly upward. 10 is an inner tank consisting of a side plate 11 and a ceiling 12, and the lower end of the side plate 11 is fixed to the bottom plate 2 of the outer tank 1 to form the outer tank 1.
The ceiling 12 is sloped upward toward the center. The side plates 11 and 3 of the inner and outer tanks 10 and 1 are connected at two locations above and below by annular diaphragms 13 and 13 with an I cross section to form a double hull structure.
Holes through which water W passes are appropriately bored in the web portion 13. 11a is a communication hole provided at the lower end of the side plate 11 and communicating with the outer tank 1. Reference numeral 15 denotes an oil L injection/discharge pipe connected to the center of the ceiling 12 of the inner tank 11, through which oil L is injected/discharged by a pump device 16. and injection and discharge pipe 1
A baffle plate 8 is provided at the opening in the ceiling 12 of 5 in the same way as in the case of the water supply pipe 5. Reference numeral 17 denotes an air vent valve provided at the highest position of the oil injection and discharge pipe 15. 18 is an overflow pipe for water W provided at the upper end of the outer tank side plate 3. 19
is a liquid level detector that detects an interface A between oil L and water W, which is provided at the lower end of the side plate 11 of the inner tank 10.

When filling oil L into this oil storage tank for the first time, the air vent valve 17 is opened, and the water W in the water storage tank 6 is first supplied from the outer tank 1 with the pump 7 until it overflows, and then the water is poured into the inner tank. tank 1
0 is filled with water W, and the inner tank 10 is filled with water W.
Completely surround with water W. Then the pump device 16
When the air is removed from the rising part of the discharge pipe 15, the air release valve 17 is closed and the oil L is injected under pressure. As a result, the water W in the inner tank 10
is pushed out by the supplied oil L, and the interface A between the oil L and water W in the inner tank 10 is successively lowered, and the pushed out water W is returned to the water storage tank 6 through the overflow pipe 18. In this case, since the baffle plate 8 is provided at the opening end of the oil injection pipe 15, the interface A between the oil L and the water W descends without being disturbed. When the liquid level detector 19 detects that the boundary surface A has fallen to a predetermined position, the pump device 16 is stopped. In this way, the oil L is stored in the inner tank 10 in a state floating on the water W. Next, when discharging the stored oil L, the water pump 7 is activated to maintain the overflow state from the overflow pipe 18, and the pump device 16 is activated to discharge the oil L from the oil discharge pipe 15. This prevents the interior of the inner tank 10 from becoming a negative pressure, and the inner tank 10 can always maintain a state surrounded by water W. Also in this case, since the baffle plate 8 is provided at the open end of the water supply pipe 5, the boundary surface A gradually rises without being disturbed. The second and subsequent oil filling and draining are performed in the same manner as above. Also, inside and outside tank 1
When inspecting and cleaning 0 and 1, first drain the stored oil L as described above, then use the water W feed pipe 5 to drain the water W in the tank 1 and perform the inspection. , clean.

Note that the inner and outer tanks 10, 1 are not limited to being made of steel plates.
It may be made of concrete or may be underground.
The water surrounding the inner tank is not limited to water, but may be any liquid that is non-flammable and heavier than oil. Also, water tank 6
Usually, there only needs to be one tank in an oil storage base with a group of tanks, but it is also possible to use a pond, a river, or the sea. Note that it is also possible to easily modify an existing tank to the tank structure of the present invention.

The double-hull type water-enclosed oil storage tank of the present invention is as described above, and has the following effects.

(1) The side plates of the inner and outer tanks have a double-hull structure connected by diaphragms, etc., and are extremely rigid. Therefore, it has strong resistance to wind, so there is no need to install a weed guard as in the past.

(2) Since the oil is stored floating on water in the inner tank and there is no breathing effect of vapor, vapor loss can be completely eliminated. Therefore, there is no problem of pollution due to vapor discharge, and there is no risk of explosion due to mixing of vapor and air.

(3) Since the inner tank is completely surrounded by water, it is extremely resistant to fire spread and self-fire.

(4) The inner tank is completely surrounded by water, which is heavier than oil, so even in the event of damage, the oil will only float to the surface within the outer tank and will not leak out of the tank. Furthermore, even if the outer tank is damaged due to an earthquake, the first thing that flows out is water.
Oil spills can be prevented by taking measures such as transferring the oil to another tank before it begins to spill.

(5) There is no need to install a weather hood or seal, which is a problem with floating roof tanks, and there is no need to consider rainwater at all. Furthermore, there is no problem even if the surface of the water freezes in cold regions.

(6) The oil in the internal tank has nothing to do with the increase in sloshing during an earthquake, and is also effective against sloshing.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Outer tank, 2...Bottom plate, 3...Side plate of outer tank, 5...Water supply pipe, 10...Inner tank, 11...
Side plate of inner tank, 11a...Communication hole, 12...Ceiling, 13...Diaphragm, 15...Oil injection and discharge pipe, 18...Overflow pipe, L...Oil, W...Water.

Claims (1)

[Claims] 1. A double-hull structure is provided by fixing the side plate of the inner tank, which has an oil injection and discharge pipe connected to the ceiling in the outer tank with an open top, to the bottom plate of the outer tank, and connecting the inner and outer tank side plates with a diaphragm, etc., and The bottom plate of the outer tank is provided so as to be inclined downward toward the center, and a water supply pipe surrounding the inner tank is connected to the center of the bottom plate, and an overflow pipe is provided at the upper end of the outer tank. A double-hull type water-encased oil storage tank characterized in that a communication hole communicating with an outer tank is provided at the lower end so that oil is stored in the inner tank while floating on water.