Method for protecting inside bottom of liquid storage, and structure for protecting inside bottom of liquid storage

Abstract

To effectively prevent generation of harmful influence by separating storage liquid or liquid containing these due to secular change or the like to gather on the inside bottom of the container to react with constituent materials of the inside bottom of the container.SOLUTION: The storage liquid is a substance that reacts alone with the material constituting the inner bottom of the container, or the included liquid contained in the storage liquid reacts with the material constituting the inner bottom of the container, and when the included liquid has a greater specific gravity than the storage liquid, a stagnant liquid with an even greater specific gravity than the storage liquid and the included liquid is retained at the inner bottom of the container to prevent the reaction between the storage liquid or the included liquid and the material constituting the inner bottom of the container.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for protecting the inner bottom of a liquid storage container and a structure for protecting the inner bottom of a liquid storage container, and more specifically, to a method for protecting the inner bottom of a liquid storage container and a structure for protecting the inner bottom of a liquid storage container, which prevents the inner bottom of a container such as a tank for storing liquid such as crude oil from undergoing a chemical reaction such as oxidation with the stored liquid (e.g., crude oil) or liquids contained in the stored liquid, such as moisture, resulting in damage such as rust, by retaining a liquid with a higher specific gravity than the stored liquid and the liquids contained in the stored liquid in the inner bottom of such a container, thereby preventing contact between the stored liquid or liquids contained in the stored liquid and the inner bottom of the container and preventing or suppressing harmful chemical reactions, etc. [Background technology]

[0002] When storing a liquid such as crude oil in a storage container, if the liquid to be stored (storage liquid 300) contains multiple constituent substances as shown in Figure 1(A), these constituent substances may separate due to aging or other reasons to become separated substances 500, as shown in Figure 1(B), and accumulate inside the storage container 100.

[0003] For example, in the case of crude oil 310, which is a mixture of hydrocarbons of various molecular weights, as shown in FIG. 2, liquid components such as oil, asphaltene, wax, and water contained in the crude oil 310 to be stored, or solid or semi-solid precipitates consisting of sand, iron rust, etc., called crude oil sludge 505, accumulate on the inside bottom 120 of a container 100 such as a tank for storing the crude oil 310 over a long period of storage, and may chemically react with the metal that constitutes the inside bottom 120 of the container, causing harmful effects such as corrosion.

[0004] Therefore, in order to prevent corrosion and the like on the inside bottom of such containers, for example, steel materials with excellent corrosion resistance have been developed (Patent Document 1), or measures have been taken such as applying coatings to the inner surfaces, including the bottoms, of containers and structures such as storage tanks that use such steel materials (Non-Patent Document 1).

[0005] In addition, in order to protect the inside of such containers as liquid storage tanks, in addition to using corrosion-resistant steel materials or coatings, means have been disclosed, such as a corrosion prevention method for ballast tanks (Patent Document 2) and a rust prevention method for oil storage tanks (Patent Document 3), in which a fluid is suspended on the stored liquid inside the container or an oil film is formed on the inner surface of the container using rust-preventive oil. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2017 / 098701 issue [Patent Document 2] Japanese Patent Application Publication No. 9-24890 [Patent Document 3] Japanese Patent Application Publication No. 11-1784 [Non-patent literature]

[0007] [Non-Patent Document 1] Director of the Hazardous Materials Regulation Division, Fire and Disaster Management Agency: Guidelines for coating to prevent corrosion inside specific outdoor storage tanks (Notice), Fire and Disaster Management Agency No. 74, September 1, 1994 Summary of the Invention [Problem to be solved by the invention]

[0008] However, even if it is possible to reduce corrosion to a certain extent by using steel materials with excellent corrosion resistance, as described in Patent Document 1, it seems difficult to ensure sufficient reliability over the long term when used with petroleum sludge and other materials that contain a variety of substances.

[0009] Furthermore, even if corrosion-resistant steel materials and the like are painted or coated as described in Non-Patent Document 1, deterioration over time, earthquakes, poor construction, and other factors can cause damage such as peeling, swelling, wrinkles, cracks, and pinholes in the paint film or coating, which can lead to corrosion on the inside bottom of containers such as storage tanks.

[0010] Damage to these paint films and coatings is often inspected and repaired during regular open inspections of storage tanks. However, when measuring the plate thickness of the tank bottom or inspecting welds for flaws, restoration work such as stripping off the paint and repainting may be required. Since the area to be repaired is enormous, this requires a lot of time and money.

[0011] Moreover, the technology described in Patent Document 2 is characterized in that, in order to provide corrosion protection for the inner walls of a ballast tank inside a container above the seawater level inside the ballast tank, the ballast tank is made of steel material coated with a resin coating of a specified thickness, and a substance is suspended on the seawater level inside the ballast tank, the substance having a lower specific gravity than seawater, being insoluble in seawater, and being liquid at the seawater level.

[0012] However, the technology described in Patent Document 2 is intended to suppress harmful chemical reactions that occur on the inside of the storage container, in the portion facing the space on the upper surface side of the stored liquid.

[0013] Therefore, since no consideration is given to eliminating the harmful effects, such as corrosion, that the constituents of the stored liquid may have on the inside bottom of the storage container, the technology described in Patent Document 2 has the problem of not being able to adequately protect the inside bottom of the storage container.

[0014] In addition, the technology described in Patent Document 3 discloses a method for preventing rust on an oil storage tank, which is characterized by spraying a rust-preventive oil having water-separating and water-displacing properties or a mixture of the rust-preventive oil and water onto the inner surface of the oil storage tank, or by pouring the oil along the inner surface of the oil storage tank into the oil storage tank, thereby applying the rust-preventive oil to the inner surface of the oil storage tank.

[0015] However, the technology described in Patent Document 3 is intended to protect the inner surface of the container during the temporary period from the water drainage test of the crude oil tank until the storage of the crude oil, and involves applying liquid rust-preventive oil to the inside of the container, including the inside bottom of the container, but does not take into consideration rust prevention after the crude oil, which is the stored liquid, has been stored. Therefore, it is not possible to prevent the generation of rust due to oxidation reactions caused by contact between the inside bottom of the container and substances such as moisture that separate from stored liquids such as crude oil over time.

[0016] Therefore, the present invention has been made in consideration of the above-mentioned circumstances, and aims to effectively prevent the stored liquid or these constituent substances from separating due to aging or other reasons when the stored liquid contains multiple constituent substances, accumulating at the bottom inside the container, and reacting with the constituent substances at the bottom inside the container, causing harmful effects. [Means for solving the problem]

[0017] In order to solve the above problems, the present invention provides a method for protecting the inner bottom of a liquid storage container, characterized in that when the stored liquid alone reacts with a constituent material of the inner bottom of the liquid storage container, or a contained liquid contained in the stored liquid reacts with a constituent material of the inner bottom of the liquid storage container, and the contained liquid has a higher specific gravity than the stored liquid, a retained liquid having a higher specific gravity than the stored liquid and the contained liquid is retained at the inner bottom of the liquid storage container, thereby preventing the stored liquid or the contained liquid from reacting with the constituent material of the inner bottom of the container.

[0018] In addition, in order to solve the above-mentioned problems, the present invention provides a structure for protecting the inner bottom of a liquid storage container, characterized in that when the stored liquid alone reacts with a constituent material of the inner bottom of the liquid storage container, or a contained liquid contained in the stored liquid reacts with a constituent material of the inner bottom of the liquid storage container, and the contained liquid has a higher specific gravity than the stored liquid, the stored liquid and the retained liquid having an even higher specific gravity than the contained liquid are retained at the inner bottom of the liquid storage container, thereby preventing the stored liquid or the contained liquid from reacting with the constituent material of the inner bottom of the container.

[0019] Furthermore, the above problem is solved even more effectively by the retained liquid being insoluble in the stored liquid, the contained liquid, and the constituent material of the inner bottom of the container, or by the retained liquid having a viscosity that allows it to remain without gaps in recesses at room temperature where the contained liquid, which has a higher specific gravity than the stored liquid, tends to accumulate if the inner bottom of the container is uneven, or by the liquid storage container being a crude oil tank, the stored liquid being crude oil, the contained liquid being water, the retained liquid being liquid epoxy resin, the constituent material of the inner bottom of the container being metal, the reaction being an oxidation reaction, and the viscosity being approximately the same as that of the water at room temperature.

[0020] Furthermore, the above problem can be solved even more effectively by, when an inlet and outlet for the stored liquid are provided on the side of the liquid storage container, the stagnant liquid flows in and out through the inlet and outlet, and the upper surface of the flow-in stagnant liquid is formed below the inlet and outlet, or by, when one or more ring-shaped anti-sloshing plates for stagnant liquid are provided along the inside of the liquid storage container, and the stagnant liquid is filled up to a height below the uppermost anti-sloshing plate for stagnant liquid, or, when the liquid storage container is provided with an inlet and outlet for the stored liquid, by, when one or more inlet and outlets for the stagnant liquid are provided below the inlet and outlet for the stored liquid and below the uppermost anti-sloshing plate for stagnant liquid. Effect of the Invention

[0021] In the present invention, as described above, by retaining a retained liquid such as liquid polyethylene, which has a higher specific gravity than the stored liquid or the water-containing liquid contained in the crude oil that becomes the stored liquid, in the inner bottom of the liquid storage container, it is possible to prevent or suppress direct contact between the metal or the like that constitutes the inner bottom of the liquid storage container and the water-containing liquid.

[0022] Therefore, according to the present invention, it is possible to prevent or suppress the occurrence of rust due to oxidation reactions, etc., caused by contact between the stored liquid or the metal, etc. that constitutes the inner bottom of the liquid storage container and the contained liquid such as moisture contained in the stored liquid such as crude oil.

[0023] Furthermore, by configuring it in this manner, even if the inner bottom of the liquid storage container is made of a coating made of a metal material or the like and the coating deteriorates or peels off, it is possible to prevent retained liquids such as liquid polyethylene from entering the coated or peeled off part and coming into contact with contained liquids such as moisture contained in stored liquids such as crude oil, making it possible to prevent rusting of the inner bottom of the liquid storage container for a longer period of time than before, and extend the time between re-inspections. [Brief description of the drawings]

[0024] [Figure 1] This is a cross-sectional view of a liquid storage container showing an example of how the liquid contained in the liquid stored in the container separates due to changes over time. (A) shows the state immediately after storage, and (B) shows the state after the changes. [Diagram 2] FIG. 1 is a cross-sectional view of a liquid storage vessel showing an example in which crude oil sludge has been separated from crude oil stored in the vessel due to aging. [Diagram 3] These are cross-sectional views of liquid storage containers showing examples of a configuration according to the present invention in which a stored liquid is stored in the liquid storage container and stagnant liquid is retained on the inner bottom of the liquid storage container below the stored liquid, thereby preventing direct contact between the stored liquid and the inner bottom of the liquid storage container. (A) shows an example in which the respective liquids are injected into the storage container so that a stagnant liquid layer is formed below the stored liquid layer, and (B) shows an example in which a separated liquid layer is formed below the stored liquid layer, and a stagnant liquid layer is formed further below that. [Figure 4] 1 is a cross-sectional view of a liquid storage container showing an example in which an inlet / outlet for stored liquid is provided on a side surface of the storage container. [Diagram 5] 1 is a cross-sectional view of a liquid storage container showing an example in which an inlet / outlet for the stored liquid is provided on the side of the storage container and an anti-sloshing plate is provided on the inside of the liquid storage container. [Figure 6] 1 is a cross-sectional view of a storage container showing an example in which an inlet / outlet for stored liquid and an inlet / outlet for stagnant liquid are provided on the side of the storage container, and an anti-sloshing plate is provided on the inside of the liquid storage container. [Figure 7] (A) is a photograph showing a test piece of iron, (B) is a photograph showing an example of Pattern 1 (control example) when crude oil is being poured into the liquid storage container to start the test, and (C) is a photograph showing an example of Pattern 2 (embodiment example) when crude oil is being poured into the liquid storage container to start the test. [Figure 8] These are photographs of the inside of the liquid storage container immediately after the start of the test; (A) shows pattern 1 and (B) shows pattern 2. [Figure 9](A) is a photograph of the inside of the liquid storage container in the pattern 1 state five weeks after the start of the test, and (B) is an enlarged view of the test piece area. [Figure 10] (A) is a photograph of the inside of the liquid storage container in the pattern 2 state five weeks after the start of the test, and (B) is an enlarged view of the test piece area. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the method for protecting the inner bottom of a liquid storage container and the structure for protecting the inner bottom of a liquid storage container according to the present invention will be described in more detail with reference to the drawings.

[0026] Note that the drawings referred to below show an overview of the present invention, and some of the detailed proportions and notations of common structures may be emphasized or omitted to facilitate understanding.

[0027] The method and structure for protecting the inner bottom of a liquid storage container according to the present invention first causes a retained liquid having a higher specific gravity than the stored liquid and the contained liquid such as water contained in the stored liquid to retain in the inner bottom of the container in order to protect the inner bottom of the liquid storage container. Therefore, even if the contained liquid such as water is separated from the stored liquid and becomes a separated liquid due to aging or the like, the separated liquid is prevented or inhibited from coming into contact with the inner bottom of the container, thereby preventing harmful effects such as rust from occurring on the inner bottom of the container. (Note that, although the contained liquid and the separated liquid are basically the same, in the explanation of the present invention, the liquid contained in the stored liquid is referred to as the contained liquid, and the liquid separated from the stored liquid due to aging or the like may be referred to as the separated liquid.) Therefore, in the present invention, for example, as shown generally in FIG. 3(A), first, the storage liquid 300 and the stagnant liquid 700 are injected into the storage container 100 so that a stagnant liquid layer 720 is formed below the storage liquid layer 320.

[0028] In this way, a stagnant liquid layer 720 is formed below the stored liquid layer 320, and since the stored liquid 300 and the inner bottom 120 of the container do not come into direct contact with each other, harmful chemical reactions do not occur between the stored liquid 300 and the inner bottom 120 of the container, and the inner bottom 120 of the container can be protected.

[0029] Furthermore, if the stored liquid 300 flowing into the container in this manner contains contained liquid X (not shown), as a result of aging, the contained liquid X contained in the stored liquid 300 separates to become separated liquid 510 below the stored liquid 300 layer, forming a separated liquid layer 520, as shown in FIG. 3(B). However, since there is a stagnant liquid layer 720 below the separated liquid layer 520, contact between the separated liquid layer 520 and the inner bottom 120 of the container due to the separated liquid 510 is prevented or suppressed.

[0030] Therefore, no harmful chemical reaction occurs between the separated liquid 510 derived from the contained liquid X and the inner bottom portion 120 of the container, and the inner bottom portion 120 of the container can be protected.

[0031] Therefore, the components of the present invention will be described in order below.

[0032] (1) Containers used in the present invention First, the liquid storage container 100 used in the present invention is used to store the liquid 300 for a required period of time, and can be of any type and can be named as long as it can store the liquid 300. In addition, the shape of the container can be cylindrical or of any other type.

[0033] Therefore, the container used in the present invention may be anything from a beaker to a large structure such as a crude oil tank.

[0034] Furthermore, the present invention is adapted to protect the inside bottom portion of the container, including the inside bottom surface of the container, among the containers used.

[0035] That is, in the present invention, by retaining stagnant liquid below the stored liquid in the container, the stagnant liquid covers the inner bottom of the container, thereby achieving protection of the inner bottom of the container.

[0036] The inner bottom of the container referred to here corresponds to the inner bottom surface of the container where the retained liquid accumulates, and the part of the inner side surface of the container that rises from the periphery of the inner bottom surface and has a height corresponding to the amount of retained liquid.

[0037] Therefore, for example, in the case of a container having a cross-section as shown in Figure 3(B), the inner part of the container within the region shown inside the thick U-shaped line in the figure corresponds to this, and by the retained liquid retained in this part, the inner bottom of the container is protected from the stored liquid or liquid contained in the stored liquid (or separated liquid).

[0038] Furthermore, there are no particular limitations on the material of construction of the liquid storage container 100 used in the present invention, and it may be glass such as that used for beakers, or steel used for structures such as crude oil tanks.

[0039] And since the present invention is directed to protecting the inside bottom of a liquid storage container, it does not matter whether the inside bottom of such a container is coated like a crude oil tank.

[0040] Therefore, if there is no coating on the inside bottom of the container, the constituent materials of the container will come into direct contact with the stored material, but by using the present invention, this effect can be eliminated by retaining the stagnant liquid.

[0041] Furthermore, if the inside bottom of the container is coated with some kind of coating, even if the coating of the container is damaged due to aging or the like, the retained liquid can penetrate into the deteriorated parts of the coating to prevent contact between the contained liquid X or the separated liquid 510 and the inside bottom 120 of the container, thereby protecting the inside bottom 120 of the container. Furthermore, if the inside bottom of the container is coated with some kind of coating, it is of course necessary that such a coating agent and the retained substance of the present invention do not interact with each other.

[0042] In addition, the liquid storage container used in the present invention can also be provided with an inlet / outlet 130 for allowing the stored liquid 300 to flow in and out of the container 100, an inlet / outlet 170 for allowing the stagnant liquid 700 to flow in and out, or a sloshing prevention plate 190 for preventing sloshing of the stagnant liquid 700, as described below.

[0043] (2) Relationship between the stored liquid in the present invention and the contained or separated liquid, the retained liquid, and the material constituting the inner bottom of the container Next, the relationship between the stored liquid, the contained liquid or separated liquid, the retained liquid, and the material constituting the inside bottom of the container in the present invention will be described.

[0044] In the present invention, the liquid stored in a liquid storage container is referred to as the stored liquid, and as described above, the liquid substance contained in the stored liquid is referred to as the contained liquid, the contained liquid that has separated from the stored liquid is referred to as the separated liquid, and the liquid that is in contact with and retained in the inner bottom of the storage container is referred to as the retained liquid.

[0045] Among these, the stored liquid is not particularly limited and may be of any type, and is not necessarily limited to a mixture containing a plurality of liquid components, and may be a liquid of a single component.

[0046] This is to prevent even a single-component liquid from causing a harmful reaction when it comes into contact with the inside bottom of the container.

[0047] Similarly, there is no particular limitation on the contained liquid (or separated liquid) contained in the stored liquid, but for example, if the stored liquid is assumed to be a mixture of hydrocarbons with multiple molecular weights such as crude oil, a contained liquid or separated liquid such as water is assumed. Note that the term water is used here to mean the aqueous phase that separates from crude oil or the like due to aging or the like, and it is intended to mean pure water or an aqueous solution containing a hydrophilic substance.

[0048] Additionally, the present invention provides that the stored liquid or any liquids contained therein become a separating liquid, preventing any deleterious reactions due to contact with the inside bottom of the container.

[0049] Therefore, the present invention is applicable when the stored liquid is a substance that reacts with the constituent material of the inner bottom of the container by itself, or when the stored liquid contains a contained liquid that reacts with the constituent material of the inner bottom of the container, and the contained liquid has a higher specific gravity than the stored liquid. If such a reaction (especially a harmful reaction) does not occur, there is no need to apply the present invention. In addition, the reason why the above-mentioned specific gravity is set as a condition is that the present invention aims to prevent a contained liquid (or a separated liquid) that is heavier than the specific gravity of the stored liquid from contacting the inner bottom of the container, and does not apply to separated liquids that do not accumulate at the inner bottom of the container due to their light specific gravity.

[0050] Here, the constituent material of the inside bottom of the container includes, as described above, the material that constitutes the inside of the container itself, or, if the material is coated with a coating agent, the material of the coating agent.

[0051] The harmful reaction referred to here is not particularly limited as long as it causes deterioration or damage to the inside bottom of the container, but from a practical standpoint, it is mainly exemplified by harmful chemical reactions. For example, if the material constituting the inside bottom of the container is metal, an oxidation reaction is assumed, and the oxidation reaction referred to here broadly includes reactions that corrode metal materials. Therefore, the present invention makes it possible to prevent corrosion of the inside bottom of the container due to such oxidation reactions.

[0052] Next, the retained liquid is a liquid that is retained in the bottommost part of the storage container, and is retained in order to prevent or suppress direct contact between the above-mentioned stored liquid, contained liquid, or separated liquid and the inner bottom of the container.

[0053] Therefore, the retained liquid needs to have a higher specific gravity than the stored liquid, and if the stored liquid contains contained liquid, the retained liquid needs to have a higher specific gravity than the contained liquid (or separated liquid).

[0054] The retained liquid must not undergo any harmful chemical reactions with the inside bottom of the container, including the inside bottom surface of the container, and it must not undergo any harmful reactions with the stored liquid and the liquid contained therein (or separated liquid). The present invention prevents harmful reactions from occurring due to contact between the stored liquid or the liquid contained therein (or separated liquid) and the inside bottom of the container, and the retained liquid that remains between the stored liquid or the liquid contained therein (or separated liquid) and the inside bottom of the container must naturally not undergo any harmful reactions with them.

[0055] Here, harmful reactions are basically the same as those mentioned above, but what is meant is that no significant reactions that would cause harmful reactions such as corrosion will occur on the inside of the container, including the inner bottom of the container, during the expected storage period, and does not strictly mean that no reactions will occur.

[0056] Similarly, it is desirable that the retained liquid is incompatible with the stored liquid and the contained liquid (or separated liquid) during the expected storage period. Compatibility prevents the stored liquid or the contained liquid (or separated liquid) from dissolving in the retained liquid and adversely affecting the inside bottom of the container.

[0057] However, as described above, the term "incompatible" does not strictly mean that there is absolutely no compatibility. As long as the incompatibility is sufficient to have a significant effect during the expected storage period, there is no problem in practical use.

[0058] Therefore, the retained liquid is not particularly limited as long as it has these properties, and can be selected depending on the stored liquid or contained liquid (or separated liquid) and the material of the inside bottom of the container, etc. Specifically, for example, when a crude oil tank is assumed to be the storage container, crude oil is assumed to be the stored liquid, and the material of the inside bottom of the container is assumed to be steel (or a steel material with a coating), a liquid epoxy resin or the like can be used.

[0059] That is, when the stored liquid is crude oil, it is expected that the liquid may contain water or other liquids (or separated liquids), and the water or other liquids (or separated liquids) may corrode the steel material of the crude oil tank.

[0060] However, when this epoxy resin is used as the retained liquid, by retaining the retained liquid at the inside bottom of the crude oil tank, even if contained liquid such as water (or separated liquid) separates, it cannot come into contact with the inside bottom of the crude oil tank, thereby preventing rust.

[0061] In addition, the liquid epoxy resin is exemplified here in the case where crude oil is assumed to be the stored liquid, and there is no particular limitation as long as it is liquid during the storage period and does not cause harmful reactions with the stored liquid, crude oil, contained liquid (or separated liquid), water, etc., and the constituent materials of the inside bottom of the container, as described above. Therefore, for example, dichloromethane, chloroform, tetrabromoethane, isocyanate, etc. are assumed to be used as liquids that are heavier than water and not water-soluble, but care must be taken because some of them are harmful to the human body or difficult to obtain or handle.

[0062] Furthermore, the retained liquid must have a viscosity that allows it to remain without gaps even if there are gaps or unevenness on the inside bottom of the container due to cracks in the coating, etc., at the normal temperature when the stored liquid is stored in the container (in the case of a crude oil tank, etc., this is generally room temperature (20°C ± 15°C)). In other words, for example, if the inside bottom of the container has unevenness, the retained liquid must have a viscosity that allows it to remain without gaps in the recesses where contained liquid (or separated liquid) with a higher specific gravity than the stored liquid is likely to accumulate. This is to prevent gaps from being created between the retained liquid and the inside of the container, so that the stored liquid, etc., does not enter into those gaps.

[0063] Therefore, the desired viscosity depends on what is selected for the storage liquid, the contained liquid or separated liquid, and the retained liquid. For example, if a crude oil tank is assumed as the storage container, crude oil as the storage liquid, and liquid epoxy resin or the like as the retained liquid, the viscosity of the retained fluid is preferably the same as that of water at room temperature, or 0.1 mPa·s or more and 1000 mPa·s or less. At present, substances with a viscosity lower than 0.1 mPa·s do not exist or are difficult to produce, and if the viscosity is higher than 1000 mPa·s, it will not be possible to pump it with a pump and it will be difficult to enter cracks in the coating, etc. Therefore, although it depends on the size of the storage container, for example, as in the example described below, in the case of a retained liquid of about 600 mPa·s, which is within the above range, it can be introduced by gravity without a pump, eliminating the need for additional equipment, and the lower the viscosity, the faster the flow rate will be, which will reduce the overall work time.

[0064] The above configuration is the basic element of the present invention, but the following configurations can also be added to implement the above method and structure.

[0065] (3) Flow of stored liquid and stagnant liquid into liquid storage containers In the present invention, it is necessary to flow the stored liquid and the retained liquid into the liquid storage container, and there is no particular limitation on the means for the flow in and out. Therefore, for example, as shown in Fig. 4, it is possible to provide an inlet / outlet 130 for the stored liquid 300 on the side of the liquid storage container 100. In that case, the retained liquid 700 can be caused to flow into the liquid storage container 100 from the inlet / outlet 130 after the stored liquid 300 flows in or before the stored liquid 300 flows in.

[0066] Furthermore, since the upper surface (liquid level) 730 of the retained liquid thus flowed in is formed below the inlet / outlet 130 for the stored liquid, it is possible to prevent the retained liquid 700 from flowing out together with the inflow / outflow of the stored liquid 300. Furthermore, in this case, taking into consideration that a separated liquid layer 520 in which the contained liquid X separates from the stored liquid 300 is formed on the upper surface 730 side of the retained liquid, it is desirable to lower the liquid level 730 of the retained liquid from below the inlet / outlet 130 for the stored liquid 300 by the expected thickness of the separated liquid layer 520.

[0067] Furthermore, when filling the liquid storage container 100 with the stagnant liquid 700, it is desirable to form a turbulent flow in which the stagnant liquid 700 and the stored liquid 300 mix together, thereby preventing the stored liquid 300 from coming into contact with the inner bottom 120 of the container. For this reason, for example, as shown in Fig. 5, one or more ring-shaped anti-sloshing plates 190 for stagnant liquid can be provided along the inside of the liquid storage container 100. In this case, when multiple anti-sloshing plates (190U, 190D) are provided above and below as shown in Fig. 5, it is also possible to fill the stagnant liquid 700 up to a height equal to or lower than the uppermost anti-sloshing plate 190U for stagnant liquid.

[0068] Therefore, when such a sloshing prevention plate 190 is installed, it is possible to prevent the separated liquid 510, etc. from coming into contact with the inner bottom 120 of the storage container 100 due to liquid surface vibrations of the stored liquid 300 when the stagnant liquid 700 or the stored liquid 300 is flowing into the container, or even in the event of an external disturbance such as an earthquake.

[0069] Furthermore, as described above, when the inlet / outlet 130 for the stored liquid 300 is provided on the side surface of the liquid storage container 100 or at another location, it is also possible to provide a separate inlet / outlet 170 for the retained liquid, as shown in Fig. 6. This is to prevent the retained liquid 700 and the stored liquid 300 from mixing together, even if only temporarily, when these liquids are allowed to flow into the storage container 100.

[0070] Therefore, in such a case, it is desirable that the inlet / outlet 170 for the stagnant liquid be located below the inlet / outlet 130 for the stored liquid, and if an anti-sloshing plate 190 for stagnant liquid is provided, it is desirable that it be located below the uppermost anti-sloshing plate 190U for stagnant liquid.

[0071] It is also possible to provide multiple inlets and outlets 170 for the stagnant liquid. In this case, an inlet 170I and an outlet 170O can be provided separately, or the inlet or outlet direction can be changed not only toward the center of the storage container 100, but also from the tangent direction of the inner circumference of the storage container 100, etc., so that the stagnant liquid 700 flows along the inner circumference of the storage container 100.

[0072] In this manner, when an inlet / outlet 170 for the stagnant liquid is provided, it is possible to periodically collect samples from the inlet / outlet 170 for the stagnant liquid to check the concentration and contamination state of the stagnant liquid 700, or to recycle the stagnant liquid 700 to maintain the quality of the stagnant liquid 700. Taking into consideration the amount of separated liquid 510 obtained by separating the contained liquid X from the stored liquid 300, it is also possible to discharge the accumulated separated liquid 510 from the inlet / outlet 170 for the stagnant liquid, or to forcefully flow the stagnant liquid 700 in and out to remove some of the solids that have accumulated on the bottom 120 of the storage container, thereby cleaning the inner bottom 120 of the storage container.

[0073] In addition, it is also possible to provide an appropriate liquid level gauge to observe the liquid level positions of the stored liquid 300 in the liquid storage container 100, the separated liquid 510 resulting from separation of the contained liquid X from the stored liquid, and the stagnant liquid 700. EXAMPLES

[0074] Hereinafter, the method and structure for protecting the inner bottom of a liquid storage container according to the present invention will be specifically described based on experimental examples.

[0075] The present invention aims to protect the inner bottom of a liquid storage container, and basically adopts a method or configuration for protecting the constituent materials of the inner bottom of the storage container by providing a stagnant liquid between the inner bottom of the container and the stored liquid.

[0076] Therefore, in the experimental example, an iron test piece (iron piece) (plate thickness 0.5 mm, length 50 mm, width 12 mm) as shown in Figure 7(A), which is assumed to be the constituent material of the inner bottom of the container, was placed on the bottom of the glass container.

[0077] Then, in the container, the iron piece was submerged in 200 mL of artificial seawater (concentration 25 g / L), which is assumed to be the separating liquid (or containing liquid), and crude oil (100 g), which is assumed to be the stored liquid, was poured in (Pattern 1 (control example)), and the iron piece was submerged in liquid epoxy resin (50 g), which is assumed to be the retained liquid, and 200 mL of artificial seawater (concentration 25 g / L) and crude oil (100 g) were poured in (Pattern 2 (example)).

[0078] The artificial seawater used here was made by adding water to a base of commercially available artificial seawater, and its main components were (Cl (16,750-17,850 mg / L), Mg (1,100-1,250 mg / L), Ca (390-420 mg / L), K (350-370 mg / L)).

[0079] The crude oil used was a sample of crude oil (sludge) from the Mutsu Ogawara National Petroleum Base, and the liquid epoxy resin used was JER819 (70% bisphenol A liquid epoxy resin, 30% reactive diluent) manufactured by Mitsubishi Chemical Corporation, which has a specific gravity of 1.10 and a viscosity of approximately 200 to 600 mPa·s at room temperature.

[0080] The method of injecting crude oil and other materials into the container was as follows: in pattern 1, the iron piece was submerged in seawater beforehand, as shown in Figure 7(B), and then the crude oil was poured from above, running down the chopsticks; in pattern 2, the iron piece was submerged in liquid epoxy resin beforehand, as shown in Figure 7(C), and then the seawater and crude oil were poured in, in that order, running down the chopsticks.

[0081] Figure 8 shows the side view of the glass container immediately after it has been filled with crude oil, etc. Figure 8(A) shows an example of pattern 1, in which the iron piece is completely immersed in artificial seawater. On the other hand, Figure 8(B) shows an example of pattern 2, in which the iron piece is completely immersed in liquid epoxy resin, and it can be seen that the layers are crude oil, seawater, and liquid epoxy resin from the top, and that the crude oil and liquid epoxy resin are completely separated.

[0082] Figures 9 and 10 show the state of the storage container five days after it was filled with crude oil, etc., with Figure 9 showing an example of Pattern 1 and Figure 10 showing an example of Pattern 2.

[0083] In Fig. 9, (A) is a photograph showing the part of the storage container filled with liquid, and (B) is an enlarged view of the iron piece part in the storage container. Similarly, in Fig. 10, (A) is a photograph showing the part of the storage container filled with liquid, and (B) is an enlarged view of the iron piece part in the storage container.

[0084] As can be seen from Figures 9(A) and (B), in the case of pattern 1 (control example), obvious red rust was observed on the iron piece, whereas in the case of pattern 2 (example), no corrosion was observed on the iron piece, as shown in Figures 10(A) and (B).

[0085] Therefore, it was confirmed that the present invention can protect the inner bottom of a liquid storage container. [Explanation of symbols]

[0086] 100 Storage Container 120 Inner bottom of storage container 130 Inlet / outlet for stored liquid 170 Inlet / outlet for stagnant liquid 190 Sloshing prevention plate 300 Liquid Storage 310 Crude oil 320 Liquid Storage Layer 500 Separated substances 505 Crude oil sludge 510 Separated liquid in which the contained liquid is separated from the stored liquid 520 Separated liquid layer 700 Stagnant liquid 720 Stagnant liquid layer 730 Top surface of stagnant liquid (layer) X-containing liquid

Claims

1. 1. A method for protecting an inside bottom of a liquid storage container, comprising: The stored liquid reacts with the constituent material of the inside bottom of the liquid storage container by itself, Or, When a contained liquid contained in the stored liquid reacts with a constituent material of the inner bottom of the liquid storage container, and the contained liquid has a specific gravity greater than that of the stored liquid, By allowing a retained liquid having a specific gravity greater than that of the stored liquid and the contained liquid to remain at the inner bottom of the liquid storage container, Preventing the stored liquid or the contained liquid from reacting with the constituent material of the inner bottom of the container; 13. A method for protecting an inner bottom of a liquid storage container, comprising:

2. The method for protecting the inner bottom of a liquid storage container according to claim 1 , wherein the stagnant liquid is incompatible with the storage liquid and the contained liquid.

3. A method for protecting the inner bottom of a liquid storage container as described in claim 2, wherein, at room temperature, the retained liquid has a viscosity sufficient to allow it to remain without gaps in recesses in which the contained liquid, which has a higher specific gravity than the stored liquid, is likely to accumulate, if the inner bottom of the container is uneven.

4. A method for protecting the inner bottom of a liquid storage container described in any one of claims 1 to 3, wherein the liquid storage container is a crude oil tank, the stored liquid is crude oil, the contained liquid is water, the stagnant liquid is liquid epoxy resin, the constituent material of the inner bottom of the container is metal, the reaction is an oxidation reaction, and the viscosity is such that the viscosity of the stagnant fluid is approximately the same as that of the water at room temperature.

5. A structure for protecting the inside bottom of a liquid storage container, comprising: The stored liquid reacts with the constituent material of the inside bottom of the liquid storage container by itself, Or, When a contained liquid contained in the stored liquid reacts with a constituent material of the inner bottom of the liquid storage container, and the contained liquid has a specific gravity greater than that of the stored liquid, By allowing a retained liquid having a specific gravity greater than that of the stored liquid and the contained liquid to remain at the inner bottom of the liquid storage container, Preventing the stored or contained liquid from reacting with the constituent materials of the inner bottom of the container; A structure for protecting the inner bottom of a liquid storage container.

6. 6. The structure for protecting the inner bottom of a liquid storage container according to claim 5, wherein the stagnant liquid is insoluble in the stored liquid, the contained liquid, and the constituent materials of the inner bottom of the container.

7. A structure for protecting the inner bottom of a liquid storage container as described in claim 6, wherein, at room temperature, the retained liquid has a viscosity sufficient to allow it to remain without gaps in recesses in which the contained liquid, which has a higher specific gravity than the stored liquid, tends to accumulate, if the inner bottom of the container is uneven.

8. A structure for protecting the inner bottom of a liquid storage container described in any one of claims 5 to 7, wherein the liquid storage container is a crude oil tank, the retained liquid is crude oil, the contained liquid is moisture, the retained substance is liquid epoxy resin, the constituent material of the inner bottom of the container is metal, the reaction is an oxidation reaction, and the viscosity is such that the viscosity of the retained fluid is approximately the same as that of the moisture at room temperature.

9. In the case where an inlet / outlet for the stored liquid is provided on a side surface of the liquid storage container, the retained liquid flows in or out through the inlet / outlet, The structure for protecting the inner bottom of a liquid storage container according to claim 8 , wherein an upper surface of the flowed-in retained liquid is formed below the inlet / outlet.

10. A structure for protecting the inner bottom of a liquid storage container as described in claim 8, wherein one or more ring-shaped anti-sloshing plates for stagnant liquid are provided along the inside of the liquid storage container, and the stagnant liquid is filled to a height below the height of the uppermost anti-sloshing plate for stagnant liquid.

11. A structure for protecting the inner bottom of a liquid storage container as described in claim 10, wherein, when the liquid storage container is provided with an inlet / outlet for the stored liquid, one or more inlets / outlets for the stored liquid are provided below the inlet / outlet for the stored liquid and below the uppermost anti-sloshing plate for the stagnant liquid.

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