JPS5927437Y2 - flammable liquid storage tank - Google Patents

Description

[Detailed description of the invention] The present invention consists of packing a large number of inorganic glass-like hollow bodies or synthetic resin hollow bodies (hereinafter referred to as hollow bodies) into a bag made of synthetic resin or synthetic rubber or a bag made of ceramic fiber fabric. By floating a blanket (hereinafter referred to as the blanket) on the surface of the flammable storage liquid (hereinafter referred to as the storage liquid), the evaporation of the storage liquid is prevented, and an inert gas is sent above and below the surface of the storage liquid inside the tank. The present invention relates to a storage tank characterized in that it is equipped with equipment capable of extinguishing a tank fire or preventing the expansion of a tank fire.

The fire extinguishing method for flammable liquid storage tanks stipulated by the Fire Service Act or the Insurance Association is the homite method or the dry chemical method, but in the case of an actual fire, the homite method requires the mixing ratio of liquids A and B, In the dry chemical method, the mixing ratio of powdered chemicals and water is not always adjusted and operated ideally due to the operator's inclination to deal with an emergency situation, and as a result, the effectiveness of the chemicals cannot be fully demonstrated. It is often impossible to extinguish the fire, or it takes a long time to extinguish the fire, and the opportunity for initial extinguishment is often lost.

As described above, methods for dealing with fire emergencies cannot always be expected to be 100% effective.

To this end, the tank of the present invention was designed to simplify human operations as much as possible and to permanently install the necessary facilities.

To explain the present invention by taking the case of (1) a conical roof tank or a round roof tank as an example, in Figures 1.2.3 and 4, a blanket 5 is always placed on the surface of the stored liquid 2 in the tank 1. to prevent evaporation of the stored liquid.

In the event of a fire, a fire extinguishing ring 6.6' is provided in the tank 1 with an inert gas such as nitrogen to prevent evaporation of the stored liquid by the blanket 5.

The fire can be extinguished easily and reliably by blowing into the inner circumferential surface of the tank side plate through 6'' and blocking the inflow of air necessary for combustion of the fire.

6/, Inert gas emitted from a pipe installed in the liquid floats to the liquid surface, creates an inert gas layer between the liquid surface and the blanket, and supplies oxygen to the liquid surface. almost completely blocked.

At this time, the blanket is fortunately flexible and can maintain a sufficient seal between the blanket and the inner peripheral surface of the tank, making it possible to maintain a thicker inert gas layer than in the case of a plate-shaped material.

With the above method, even if the synthetic resin or synthetic rubber bag of the blanket is torn due to a fire,
It is possible to extinguish a fire to prevent evaporation of the stored liquid and prevent the fire from spreading by covering the liquid level of the stored liquid with the blanket remaining in the form of pieces between the large number of hollow bodies.

Note that the blanket reduces the evaporation loss of the stored liquid by preventing it from evaporating under normal conditions, and also prevents the stored liquid from flowing out of the tank by preventing the tank liquid level from fluctuating during an earthquake. This is also effective in preventing fires.

In particular, in tanks with conical roofs, when a fire ignites, an explosion occurs, and cracks or openings occur at the joint between the side panels and the roof panels, and in such cases, outside air may enter the tank. Although it is difficult to block the inflow, the device of the present invention forms a curtain of inert gas around the inner circumference of the tank side plate, and prevents the inert gas filling the cavity inside the tank from entering the tank. By flowing outside through the cracks or openings, external air can be easily blocked, and tank fires can be extinguished or fires can be prevented from spreading.

The fire extinguishing rings 6.6', 6'' are provided with blow-off holes 7 on the outer periphery of the fire extinguishing rings so that the inert gas is blown out toward the inner peripheral surface of the tank side plate.

This blow-off hole 7 may become clogged due to viscous stored liquid such as heavy oil and impurities in the stored liquid, so to prevent this, the blow-off hole 7 is made of synthetic rubber that is stable against the stored liquid. A stopper made of synthetic resin is provided, or the blow-off hole 7 is covered with a membrane made of synthetic resin or synthetic rubber that has the strength to withstand the hydraulic pressure of the stored liquid.

In this case, the blowout pressure of the inert gas in the event of a fire needs to be designed to be higher than the pressure that would remove or burst the plug or membrane.

As shown in FIGS. 4 and 5, the blanket that floats on the surface of the storage liquid is made by packing a large number of hollow bodies into a bag 4 made of synthetic resin or synthetic rubber or a bag 4 made of ceramic fiber fabric.

In this case, in view of the strength of the bag 4 and ease of fabrication, it is possible to divide the bag 4 into shapes as shown in FIG. In the case of ceramic fabric, each divided surface is closed and integrated.

In this case, the larger the capacity of the tank, the greater the number of divisions.

This division also has the effect of making the wall thickness uniform during use.

(2) In the case of a floating roof type tank, as shown in Figure 6, a fire extinguishing ring 6 for blowing out inert gas is attached to the pontoon 10 of the floating roof, and the fire extinguishing ring and the piping outside the tank are connected with a metal flexible hose. Connect by 9.

The blanket is placed between the floating roof 8 and the storage liquid level.

Fires in floating roof tanks generally occur mainly in the seal area, so in order to prevent this, a ring-shaped blanket 5 as shown in Figure 7 should be used to sufficiently cover the stored liquid level in the seal area. You can also use .

The blanket used in this invention is as shown in Figure 4.
A bag made of synthetic resin or synthetic rubber or a bag made of ceramic fiber fabric is filled with a large number of hollow bodies.

The material of the bag is polyethylene, vinyl chloride, polyester,
A coating of synthetic resin such as nylon or synthetic rubber such as neoprene is generally used, but in order to further increase the strength of the coating, a fabric coated with such synthetic resin or synthetic rubber may also be used.

Further, carbon fiber or ceramic fabric may be used in consideration of fire resistance and heat resistance.

The material used for the hollow body is inorganic glass or flame-retardant synthetic resin such as fluororesin or silicone resin.

The shape of the hollow body is preferably spherical, considering ease of handling, low frictional resistance due to movement of the hollow body itself, and less chance of damage.

In addition, when a hollow body has the same shape, the thicker the wall, the greater the strength; however, when it is packed in a bag made of synthetic resin, synthetic rubber, or ceramic fiber fabric, it will float on the surface of the stored liquid. In order to achieve this, the wall thickness is determined by considering the material of the hollow body and the specific gravity of the storage liquid.

Techniques for preventing liquid evaporation by floating only hollow objects on the liquid surface have already been found in foreign literature.

When only the hollow body is floated on the liquid surface, the thickness of the hollow body is uniform at any point on the liquid surface, which has the advantage of covering the liquid surface uniformly, but the liquid In between, the liquid rises to a considerable upper level due to capillary action, so it is not possible to completely suppress the evaporation of the liquid only by using a hollow body.

In order to prevent combustion in the event of a fire, evaporation must be suppressed almost completely, so this is inadequate.

Also, anyone can easily understand that floating only a blanket on the liquid surface is much better than a hollow body in terms of covering the evaporation mentioned above, but it is important to keep the blanket floating on the liquid surface, which is constantly rising and falling. It is difficult to maintain uniformity over the entire surface, which is also not appropriate.

In the present invention, since the blanket contains a hollow body, the advantages of both are promoted and the objective of completely covering the stored liquid level can be achieved.

Furthermore, the blanket bag has the effect of preventing the hollow body from flowing out and dissipating, and also has the effect of preventing the liquid level from fluctuating during an earthquake.

[Brief explanation of drawings]

Figure 1 is a longitudinal sectional view of a conical tank. FIG. 2 is a diagram showing a cross section taken along line AA' in FIG. 1. FIG. 3 is an enlarged view of B in FIG. Figure 4 is a plan view of the blanket. FIG. 5 is a cross-sectional view taken along line cc' in FIG. 4. Figure 6 is a longitudinal sectional view of the floating roof tank. FIG. 7 is a cross-sectional view taken through the center of the blanket in a special case of the use of FIG.

Claims (1)

[Scope of utility model registration request] A blanket made of an inorganic glass-like hollow body or a synthetic resin hollow body packed in a synthetic resin or synthetic rubber bag or a ceramic fiber fabric bag is placed above the stored liquid level, and an inert gas discharge port is placed above the liquid level in the tank. A flexible liquid storage tank characterized by being provided above and below the liquid surface.