JP2017536297A - Petroleum product storage tank and floating element for said tank - Google Patents

Abstract

The present invention relates to the field of storage tank design and can be used in the construction of light product storage tanks, preferably tanks for gasoline storage. The claimed petroleum product storage tank comprises a main body, a roof and a floating protective cover comprising a plurality of floating elements in the form of a rotating body having the same shape. Some of the floating elements of the protective cover in the tank will be placed below the surface of the liquid, and some will be placed in the gas space of the tank. A unique feature of the proposed invention is the floating element formed with a size difference of 5% or less. The floating elements constituting the floating protective cover are offset from the geometric center of the floating center. All elements of the protective cover are made of non-sparking metal. The technical result of the present invention is to reduce the evaporation rate and vapor concentration of the liquid, suppress the combustion process, and prevent the possibility of spark discharge and static electricity accumulation between floating elements. [Selection] Figure 1

Description

  The present invention relates to tank construction and can be used to construct a storage tank for light petroleum products, preferably a storage tank for gasoline storage.

  In petroleum product storage tanks currently operated to store petroleum products without floating covers or pontoons, intensive evaporation of the petroleum products occurs on the liquid surface and explodes in the gas space of the tank A volatile and flammable vapor mixture. Even with modern lightning protection systems, lightning that falls into the tank cannot be avoided. When lightning falls into any tank filled with petroleum products, explosions and fires occur, causing enormous losses as well as injuries and deaths.

  There are known methods of manufacturing single-disk floating covers having circular pontoons, radial and circular floats, or ring-shaped pontoons and point floats, where the central part of the floating cover comprises individual sheets, ring-shaped pontoons, Radial buoys, ring buoys are provided as discrete elements such as airtight and sealed units (compartments), profiles or box girders, bottomless boxes, respectively. Radial, circular, point floats, etc. are uniformly arranged over the entire cover area. [RU2200120, B65D88 / 34, 10.03.2003; GB11191461A, B65D88 / 34, 13.05.1970, RU2127216 C1, B65D88 / 34, 10.03.1999, RU2163559 C1, B65D88 / 34, 27.02.2001 ]. A frame, a floating cover pontoon, and the like are gathered in the lower rack. The frame layer at the center is expanded and welded together. Radial and circular or point floating bodies are welded to the widened central portion of the floating cover. The completed center of the floating cover is welded to the pontoon ring.

  The main drawbacks of such a cover are that the labor strength for construction is significant, the portability is low, and the metal strength is high. In tanks using such pontoons, the problem of forming explosive and flammable vapor mixtures is significantly reduced, but still remains. In such a tank, the pontoon may be distorted in the tank due to the discharge load or lightning strike of the petroleum product, and the pontoon stops applying its protective function (so-called rigid pontoon).

  The invention [EP2530032 A1, B65D88 / 34, 01.06.2012] includes a cover made up of independent flexible compartments in which spherical bodies and the like are arranged. Certain spheres or the like may have different diameters so as to condense the liquid margin due to evaporation into the gas space of the tank. However, since a spherical body having a small diameter is actually shown by the action of gravity, vibration or the like always falls under a spherical body having a large diameter and does not overlap with a space between the spherical bodies having a large diameter. Also, if the compartments are filled in a confused state with spheres of various diameters, etc., a regular structure having a minimum size of empty cells formed by the surface of the spheres etc. will not be formed. However, the perforated cover section is reduced but does not prevent liquid evaporation. In addition, according to the study by the present inventors, not only the overlap of the liquid surface by the cover located in the plane of the liquid surface is very important, but also the overlap in the gas space on the liquid surface plays an important role. . But if any structure, such as an element of an automatic digestion system, where lightning strikes are most likely to cause an explosion in the gas space of the tank, such a cover was submerged and burned Stop playing a protective role in reducing evaporation into the gas space of the tank.

  An invention [US12533218, B65D88 / 34, 31.07.2008] presenting a floating barrier for reducing the evaporation of a liquid product comprising a floating element having a polyhedral form of cross-section is known. Although the present invention solves the problem of evaporation reduction as the previously described invention, it cannot solve the problem of phlegmatization of the combustion process in the possible combustion of liquid and air mixtures. In the specific invention, the problem that the liquid surface overlaps the tank wall is not solved. The evaporation of the liquid product at the tank wall will increase and harmful liquid and air mixtures will collect in the gas space of the tank. Also, filling the tank in a mess with the floating elements mentioned in this invention damages the exact sequence of dense element installation "end to end", which inevitably results in an increase in the rate of liquid evaporation. The possibility is quite high.

  The invention [US8616398 B2, B65D 90/22, 25.09.2012] is most closely related to the published invention in which a floating barrier to prevent liquid evaporation is manufactured in a floating body set. However, as in the invention [EP2530032 A1, B65D88 / 34, 01.06.2012], a sphere having a small diameter always falls under a sphere having a large diameter due to gravity and vibration, and the large diameter is reduced. Does not overlap with the space between the spherical bodies. Also, if the tank is filled in a confused state with spheres of various diameters, etc., a regular structure having a minimum size of empty cells formed by the surface of the spheres etc. will not be formed. However, perforated cover sections reduce but do not prevent liquid evaporation. In addition, according to the study by the present inventors, not only the overlap of the liquid surface by the cover located in the plane of the liquid surface is very important, but also the overlap in the gas space on the liquid surface plays an important role. However, if any structure, such as an element of an automatic digestion system, where the explosion is most likely to occur in the gas space of the tank due to lightning or electrostatic discharge, for example, it will be pre-arranged such as a sphere The installation is also damaged. Also, at the time of liquid discharge-when injecting into the tank, the spheres will move relative to each other and rotate about the geometric axis, so that the flammable liquid is against the surface of the sphere Adhesion and evaporation increase. In addition, the multilayered structure of the spheroid wall disclosed in the invention [US8616398 B2, B65D 90/22, 25.09.2012] uses various plastics and resins, and even if an antistatic coating is applied. It is not possible to completely prevent the accumulation of static electricity and the occurrence of discharge, which cause ignition or explosion of the steam-air mixture. This is confirmed by the introduction of appropriate revisions to the regulatory document on the prohibition of the use of plastics and other polymer products in petroleum product tanks and other tanks.

The object of the present invention is therefore to produce a storage tank for petroleum products which does not have the above drawbacks. The technical results are as follows:
1) A reduction in the volume of the vapor mixture formed by the evaporation of petroleum products, ie a reduction in the concentration of liquid vapor in the tank gas space;
2) Providing slowing down of the combustion process in case of fire or lightning strike;
3) Possible accumulation of electrostatic discharge between floating bodies, etc. and suppression of occurrence of spark discharge.

  In order to not only solve the above-mentioned problems, but also to achieve the mentioned technical results, a petroleum product storage tank composed of a floating protective coating film consisting of a body, a shell and a number of floating elements is provided. Is done. The floating element is manufactured in a rotating body of the same shape. Some of the floating elements in the tank are arranged below the liquid surface and some are arranged in the gas space of the tank. A unique feature of the proposed invention is a floating element with a size difference of 5% or less. The floating elements that make up the floating protective coating film then offset the flotation center from their geometric center. All elements of the protective coating are made of non-sparkling metal.

  It is also proposed to arrange floating elements that form no more than four layers in the gas space.

  It is also proposed to arrange floating elements that form 1.5 or more layers in the liquid.

  Similarly, a grid with cells smaller than the diameter of the floating element can be installed at the top of the tank.

  Internal collaring can also be applied to the top of the tank.

  In the lower part of the tank above the liquid discharge-injection level, a grid with cells smaller than the diameter of the floating element can be installed.

  The floating element constituting the floating protective coating film can be made of aluminum or an aluminum alloy.

  The floating element can be made of a ceramic coating film of aluminum oxide or stainless steel.

  A hydrophobic coating can be applied to the surface of the floating element.

  The ratio of the maximum diameter of the rotating body to the wall thickness is preferably at least 50.

  It is also proposed to produce a floating element with a minimum diameter of 10 mm or more.

  It is also proposed to produce a floating element having a maximum diameter of 60 mm or less.

  It is also proposed to produce oblong, ellipsoidal or oval floating elements.

The gist of the present invention will become apparent from the drawings.
FIG. 1 shows the schematic appearance of a tank covered with a cover. FIG. 2 is a cross-sectional view A of FIG. 3 is a cross-sectional view A of FIG. FIG. 4 is a cross-sectional view of some possible forms of a floating element. FIG. 5 is a cross-sectional view of some possible forms of a floating element. FIG. 6 is a cross-sectional view of some possible forms of a floating element. FIG. 7 is a cross-sectional view of some possible forms of a floating element. FIG. 8 is a cross-sectional view of some possible forms of floating elements. FIG. 9 is a flowchart of the evaporation rate.

  The petroleum product storage tank 1 includes a cover 2 and a floating protective coating film 3 composed of a number of floating elements 4, some of which are located in the liquid 5, ie below the liquid surface 6. However, a part is arranged on the liquid surface 6, that is, in the gas space 7 (FIG. 1). A grid 8 (FIG. 2) or a collar 9 (FIG. 3) is installed at the top of the tank. The floating centers 10 of the floating elements 4 are offset from their geometric center 11 (FIGS. 4-8). In the lower part of the tank above the discharge-injection level, a grid 5 with perforated cells smaller than the diameter of the floating element 4 can be installed.

  The tank 1 having the cover 2 and the floating protective coating film 3 operates in the following manner.

  Of course, when the floating element 4 is filled into the tank 1 filled with the liquid 5 (petroleum product), these elements are distributed in a confusing manner in the tank when the liquid 5 is injected and discharged. After that, a dense floating protective coating film 3 is formed and arranged in multiple layers.

  When the liquid surface 6 vibrates at the time of injection and discharge or explosion, the floating protective coating film 3 composed of a large number of floating elements 4 as rotating bodies of the same shape functions according to the principle of duckweed in the tank. In the event of a possible lightning strike or collapse of the cover 2 structure in the tank 1, the floating elements 4 can be separated and can scatter in the tank 1. However, when returning to confusion afterwards, these are arranged in a structure having a dense packaging (floating protective coating film 3), thereby eliminating the fire trajectory that gradually evaporates and the combustion process. Is significantly slowed down. In order to prevent the floating element 4 from being discharged through the tank 1 in the case of an explosion, a grid 8 or a collar 9 is installed at the top of the tank. The grid 8 has cells that are smaller than the diameter of the floating element 4. As shown in FIG. 3, the collar 9 is installed on the upper edge of the tank 1. The collar has no danger of a new explosion and can quickly localize and extinguish the fire. In order to reduce the risk of floating elements entering the outlet, a grid 5 with perforated cells smaller than the diameter of the floating elements is installed at the bottom of the tank above the liquid discharge-injection level.

  In order to reduce the concentration of liquid vapor in the gas space 7 of the tank 1 and to provide a slowing of the combustion process as a protective coating film 3, a floating element 4 manufactured as a rotating body is used, at which time the floating element The centers 10 are offset from their geometric center 11. For example, as shown in FIGS. 4-8, the floating element 4 can have a spherical, elliptical or oval shape. Consider further in connection with the spherical floating element 4. However, it should be understood that such considerations include other rotating bodies. When the tank is drained and injected, the spherical floating elements 4 can contact each other, rotate about their geometric center, contact the liquid 5 and have a liquid film on its surface. The membrane can evaporate and vapor penetrates into the gas space of the tank 7. To prevent this, the spherical floating elements 4 are made such that their centroids 10 are offset from their geometric center 11 (FIGS. 4-8). Thereby, the spherical floating elements 4 are uniformly oriented with respect to the liquid surface 6 and can be slightly varied with respect to their position only during tank drain-injection. Thus, the dry surface of the spherical floating element 4 is not immersed in the liquid 5 and has a respective liquid film. Also, a hydrophobic coating that prevents the capillary effect can be applied to the surface of the floating element 4. This significantly reduces evaporation.

In order to prevent the possibility of static electricity and spark discharge in the assembly of spherical floating elements 4, the spherical floating elements should be made of a non-sparking metal, mainly aluminum or an aluminum alloy. In this case, the buoyancy required for the floating element 4 of the floating protective coating film 3 can be provided. The criteria for selecting the size of the floating element 4 are the following ratios:
n = D / t,
Here, D is the outer diameter of the spherical floating element 4,
t is the width of the wall of the spherical floating element 4.

  The ratio n of the floating element diameter D to the wall thickness t should be at least 50. A preferred ratio is n = 80. . . 110. Larger ratios are not preferred because the floating wall element 4 is too thin and loses resistance to mechanical exposure. For similar reasons, the minimum diameter of the floating diameter D should be at least 10 mm. The maximum diameter D of the floating element must be not more than 60 mm. In this case, the size of the cell formed by the surface of the densely arranged floating elements 4 is smaller than the critical value, i.e. destroys the chain reaction (explosion) of the stoichiometric petroleum product and air mixture. (See Semenov NN, Chain reaction, М., Nauka, 1986). In other words, the vapor-air mixture in such a cell is exposed to any ignition source (electrostatic sparks, lightning strikes, ignition material exposure, etc.) and does not explode.

  According to the study by the present inventors, it is arranged in the gas space in order to prevent evaporation of the liquid 5 having a very high flammability and inflow of liquid vapor into the gas space 7 of the tank 1. It has been shown that the minimum number of layers of the floating element 4 should be at least four. Thereby, even if combustion in the gas space 7 of the tank 1 occurs for some reason, it is slowed down. This is explained by the fact that the evaporation rate of the liquid 5 is minimized by the overlapping of the multiple layers of floating elements 4 etc. with the liquid surface 6 and the gas space 7 above the liquid surface 6.

  Our calculations and tests show that the number of layers of floating elements 4 placed in the liquid 5 is equally important. When a possible explosion occurs in the gas space 7 and the floating elements 4 arranged in the gas space 7 are sprayed, the floating elements slow up the combustion by overlapping with the liquid surface 6 while first floating. As can be seen from the test, the floating elements 4 scattered in the tank 1 completely restore the floating protective coating film 3. The number of layers of floating elements 4 in the liquid 5 should be at least 1.5.

  The decrease in evaporation rate is well illustrated by the drawing showing the relationship between overpressure level and time achieved in tank 1 where pressure is released (FIG. 9), where “13” is a tank without floating elements “14” is a curve for a rigid pontoon, and “15” is a curve for a tank having a floating protective coating film 3 composed of a number of floating elements 4. The drawing of FIG. 9 shows that overpressure is achieved over a long period of time by the presence of the floating protective coating film 3 in which the floating element 4 is arranged in multiple layers.

In order to prevent surface corrosion of the floating elements 4, an aluminum or aluminum alloy layer should be applied to those surfaces. A preferred coating composition for the floating element is Al ₂ O ₃ . According to the studies of the present inventors, the ceramic surface coating of the floating element 4 can be applied to all overwhelming large numbers of petroleum products when originally manufactured and when various types of additives are included. It was shown that the corrosion of the metal surface is effectively prevented. These studies show the high corrosion resistance of such coatings in connection with various flammable liquids and, for benzene, completely protect the surface of the floating aluminum element 4 from corrosion.

  In order to prevent capillary effects on the surface of the floating element 4, a hydrophobic coating should be applied.

  In this way, the assigned objectives and technical results are achieved.

  FIG. 1 provides a schematic appearance of a tank covered with a cover. 2 and 3 are sectional views A of FIG. 4-8 are cross-sectional views of some possible forms of floating elements and the like. FIG. 9 is a drawing of the evaporation rate.

  In FIG. 1, “1” is a tank, “2” is a tank cover, “3” is a floating protective coating film composed of a number of floating elements 4, “5” is a liquid (petroleum product), and “6” is a liquid. “7” indicates a gas space, “8” indicates a grid, “9” indicates a color, and “12” indicates a lower grid.

  4 to 8, “10” indicates the floating center of the floating element, and “11” indicates the geometric center of the floating element 4.

  FIG. 9 provides a flow chart of the rate of liquid evaporation in a tank according to that configuration, where “13” is a curve for a tank without floating elements, “14” is a curve for a rigid pontoon tank, and “15” is a number. Figure 3 shows a curve for a tank with a floating protective coating composed of a number of floating elements.

Claims (12)

Consists of a floating protective coating film consisting of a body, a shell and a number of floating elements. , In a petroleum product storage tank, partly located in the gas space of the tank,
The floating elements have a size difference of 5% or less from each other, the floating centers are offset from their geometric center, and all the elements of the protective coating film are made of non-sparking metal. Petroleum product storage tank.   The tank according to claim 1, wherein the floating elements disposed in the gas space form four or less layers.   The tank according to claim 1, wherein the floating element or the like disposed in the liquid forms 1.5 or more layers.   The tank according to claim 1, wherein a grid having cells smaller than a diameter of the floating element is installed at an upper portion of the tank.   The tank according to claim 1, characterized in that a grid with cells smaller than the diameter of the floating element is installed in the lower part of the tank above the liquid discharge-injection level.   The tank according to claim 1, further comprising an internal collar provided at an upper portion of the tank. A floating element for a tank according to claim 1 manufactured in a rotating body,
A floating element differentiated in that the floating element is made of aluminum or an aluminum alloy.   The floating element according to claim 3, wherein the floating element is made of a ceramic coating film made of aluminum oxide or stainless steel.   The floating element according to claim 3, wherein the ratio of the maximum diameter of the rotating body to its wall thickness is at least 50. 5.   The floating element according to claim 3, wherein the floating element is manufactured to have a minimum diameter of 10 mm or more.   The floating element according to claim 3, wherein the floating element is manufactured to have a maximum diameter of 60 mm or less.   The floating element according to claim 3, wherein the floating element is in the form of a long sphere, an ellipsoid or an egg.

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