US2814406A - Liquid storage tanks - Google Patents

Description

Nov. 26, 1957 J. v. MARANCIK I LIQUID STORAGE TANKS 1 Filed NOV. 23, 1955 mw mm f 3 ijjzw wmgyw Joseph V Moran Inventor Small, Dunhama mas By ail/6}, Attorney United ,814,406 mourn STQRAGE TANKS loseph V; Marancik, Elizabeth, N. 1., assignor to Esso Research and Engineering Company, a corporation of Delaware Application November 23, 1955, Serial N 0. 548,715

4, Claims. (Cl. 220-1 This invention relates to liquid storage tanks and more particularly relates to the elimination of product contamination in concrete tanks, steel tanks or the like.

The storage of large volumes of liquid in commerce such as, for example, the storage of petroleum oil and refined products obtained therefrom is an ever present problem. Because of the limitations due to the strength of materials of construction, the size of such storage tanks resting on the ground is limited. Steel tanks have been used but such tanks become expensive when the steel is of sufiicient thickness to withstand the hydraulic pressure of the stored liquid. Also some stored liquids are corrosive and steel tanks are not. acceptable. The selection of the proper corrosion resistant metal is another problem and to build a storage tank of such metal would be prohibitive in price.

Concrete tanks have been built and used but in many cases the stored liquid product becomes contaminated by contact with the concrete surfaces of the tank. In the oil industry this is particularly true of heating oils and gasoline. Metal liners integral with the concrete wall have been used but have not proved practical in prestressed concrete tanks due to the compressive forces set up in the pre-stressing operation.

According to the present invention the stored liquidproduct is prevented from coming in contact with the concrete or metal surfaces of a storage tank by introducing a water seal between the stored liquid product and a second liquid sealing medium. The storagetank may be concrete or steel and is provided with a steel liner for providing a space between the liner and the tank to receive the second sealing medium. Where the stored liquid product is corrosive, the liner is made of an alloy material not affected by the liquid product, but it is only necessary to provide a relatively thin sheet because substantially no stress or pressure is carried by the liner.

More specifically according to this invention, a thin liner or shell is spaced very close to the wall of the tank for receiving the second sealing medium which is selected to be of substantially the same specific gravity as the liquid product stored or it may be the same material as the liquid stored if no cheap alternate or substitute is available. A surge chamber is provided at the bottom of the storage tank and adjacent to the bottom of the liner or shell. In addition a dam or weir is provided within the surge chamber to control the flow of the second sealing medium as the level of stored liquid is varied by emptying or filling of the storage tank. The surge chamber is made large enough to contain the second sealing medium when the storage tank is empty.

The concrete storage tank is buried in the ground or built in a hole dug in the ground so that the tank rests in the ground and has its sides supported by the earth.

The roof of the tank is preferably above ground or at.

ground level. The invention may be used with floating roof construction or any other type of roof. The concrete tank may be located above ground or buried in the Z,3l4,i@ Patented Nov. 26,

ground. The advantage is that buried tanks may be spaced as close as possible to one another and large volumes located in a small area. Steel or concrete tanks located above ground must be spaced one-half the diameter ormore from shell to shell. Also with the underground or buried construction, freezing of the water seal is avoided and freezing of any liquid product containing water or spoilage of the liquid product by freezing temperatures is avoided.

The present invention may also be adapted to existing storage tanks to permit storage of a greater variety of products heretofore not possible due to contamination from the concrete walls or for other reasons.

In the drawings:

Fig. 1 represents a vertical cross section of a storage tank embodyfing the principles of the present invention;

Fig. 2 represents an enlarged detailed cross section taken on line 22 of Fig. l and shows the joint before being rolled flat;

Fig. 3 represents an enlarged detail of the surge chamber at the bottom of the storage tank with parts in section to facilitate the disclosure; and- Fig. 4 represents an enlarged detail cross section taken on line 44 of Eig. 2.

Referring now to-the drawing, the reference character 10. design-ates a tank buried; or built in the ground 12. Preferably the top of the wall 14; is about level or flush with the ground 12;. The roof 16' is arranged at a level about at the ground level 12; The tank 10 may be of any shape but is preferably cylindrical with a circular roof- 16 being in the form of a shallow or fiat cone with its apex at 18. The tank It may have a removable roof 16 or the roof may have removable sections or manhole to provide holes to get in and out of the tank when necessary. The roof 16 may be made of metal or concrete. The tank 10 shown in the drawing is made of concrete but other forms of construction material may be used such as metals and alloys. The tank 10 also has a circular bottom or floor 22 which rests on the ground.

winter time is avoided. The tanks may be spaced onvery close centers not permitted by codes for tanks located above ground. By arranging the tank underground the earth or ground surrounding the vertical wall 14 acts as a support for the wall so that in reality a reinforced structure results.

Storage tank 10 is provided with a suitable inlet pipe.

for feeding or introducing liquid to be stored in the tank 10. Such an inlet pipe is shown at 24ers extending through the roof 16. A product withdrawal line 26 is shown as extending through the bottom portion of wall 14. The position of lines 24 and 26 may be changed as desired.

The tank 10 is provided on its inner vertical Wall 14 with a cylindrical shell or liner 23 which is smaller in diameter than tank 10 so that it is spaced therefrom as at 32. The shell 28 has the same contour or configuration as the tank 10 but is smaller to fit therein and provide the space 32. The shell 28 is held in spaced relation from wall 14 of the tank by any suitable means such as angle clips or bolts. For example, as shown in Fig. 2, angle clip 33 is secured in any suitable manner as by bolt 34 to concrete wall 14 of the tank. Lug 35 is securedto liner 28 and'rests or is supported on angle clip. 33. While only one clip and lug combination is shown, it is to be understoodthatanumber of these isused to.

hold the shell in proper position. Other forms of securing means may be used.

The shell 28 is held in fixed position in the tank 10. The height of shell 28 is slightly less than the height of wall 14 of tank to leave a space 36 between the bottom of shell 28 and floor 22 of tank 10 and a space 38 between the top of shell 28 and the roof 16 of the tank 10. t The shell is concentric with tank 10 and is parallel with the vertical cylindrical wall 14. In a cylindrical tank 10 where, for example, the diameter is about 150 feet,.the space 32 will be one inch or less. Where the tank 10 has a wall 14 about feet high, the distance or spacing 36 at the bottom of shell 28 is about 2 inches more or less and the distance 38 at the top of shell 28 is about 6 inches. While the size of spaces 36 and 38 is not critical, the spaces are essential in the practice of this invention and are approximately the same for all tank sizes.

The lower inner wall of shell 28 is provided with an inwardly extending horizontal annular flange portion 42. Extending downwardly from the inner edge of flange portion 42 is a vertical annular flange portion 44 which terminates a distance above the floor 22 of the tank 10 to form a space 46 directly below the bottom of flange portion 44. The horizontal flange portion 42 extends inwardly at a right angle to shell 28 above the lower end of shell 28 and the vertical flange portion 44 extends downwardly at a right angle to flange portion 42. Hence, the lower end of shell 28 as shown in Figs. 1 and 3 is of inverted U-sh ape in vertical cross section to provide a surge chamber 48. In a tank as above described and having a diameter of about 150 feet and a height of about 50 feet, the horizontal flange will be about 2% feet wide and the vertical flange 44 will be about 2 /8 feet long. These dimensions will vary with difierent sized tanks as will be presently described.

Arranged between vertical flange portion 44 and the lower end 52 of shell 28 is a vertical annular dam 54 extending upwardly from floor 22 of the tank 10. The dam is fixedly secured in any suitable manner to floor 22 and has its upper end spaced from the underside of horizontal flange portion 42 as at 56 (see also Fig. 3). The chamber between the annular angular flange formed by 42 and 44 and lower end 52 of shell 28 straddles the dam 54.

In the bottom portion of tank 10 there is provided a water seal and the level of water is shown as normally at 58 and thus submerging the lower end of vertical flange portion 44. The level of water in the water seal is below the top of dam 54. The water seal is bounded by dam 54 with the water flowing through space 46 under vertical flange portion 44. ,In a tank construction where flange portions 42 and 44 are about 2 /8 feet in size, the dam 54 will be about 2 feet or slightly less in height.

Another liquid seal is provided between the shell 28 and wall 14 of the tank 10 and the seal extends into surge chamber 48. In a specific example where a Water seal is provided with a level as at 58 and gasoline is stored in tank 10 with the gasoline having a level as at 62, the space 32 between shell 28 and wall 14 of tank 10 is filled with gasoline and the level of the gasoline in space 32 will be at 64 substantially the same as the stored gasoline with its level at 62. The liquid in space 32 is selected to have a specific gravity substantially the same as the liquid stored in tank 10 and in this way there will be no differential head between the liquids on opposite sides of shell 28, or in other words, the pressure on both sides of shell 28 is the same. The stored liquid and the sealing liquid in space 32 must of course be insoluble in water when a water seal is used.

When stored gasoline liquid is withdrawn from tank 10 through line 26 and the level 62 of stored gasoline liquid goes down, the level 64 of the sealing liquid in space 32 will also go down and the sealing liquid will flow down and through space 36 under shell 28 and will accumulate in surge chamber 48 arranged at the bottom of shell 28 between horizontal flange portion 42, vertical flange portion 44 and dam 54. The gasoline sealing liquid accumulating in surge chamber 48 forces water in the water seal down from surge chamber 48 but sufficient water is retained in the bottom of surge chamber 48 to act as a water seal. The surge chamber 48 is made of a size sulficient to hold all of the sealing liquid forced from space 32 when the gasoline is emptied out of tank 10.

In one example Where the tank 10 is feet in diameter and 50 feet high and the shell 28 is spaced about one inch from vertical wall 14 of tank 10, the volume in space 32 will be about 2000 cubic feet and so the volume of surge chamber 48 will be at least about 2000 cubic feet.

In the example where finished gasoline is stored as a product in tank 10, the sealing water-insoluble liquid in space 32 may be virgin naphtha. Other hydrocarbon fractions similar to naphtha may be used. The finished gasoline contacts only the inside of shell 28 and so is prevented from contacting the concrete wall 14. The water seal at the bottom of the tank prevents the finished gasoline from contacting the concrete floor 22. The second sealing liquid which is water insoluble is maintained in the space 32 between shell 28 and vertical wall 28 and any contamination of this sealing liquid from concrete wall 14 is retained in the water insoluble sealing liquid and is isolated from the product refined gasoline by the water seal 58.

Instead of using a concrete tank, the tank 10 may be made of metal such as iron or steel and if the liquid to be stored is corrosive or is contaminated by metal, the shell 28 will be fabricated of an alloy material or metal not affected by the product. Such a construction is relatively cheap because the alloy material need not be strong enough to act as a construction material as it carries practically no load.

As above pointed out since the stored liquid in tank 10 and the sealing liquid insoluble in water and maintained in space 32 are approximately of the same specific gravity there will be no differential pressure head between the two liquids and thus the material of shell 28 may be very thin and may be constructed with rolled edges as shown in Fig. 2 which is a horizontal section taken on line 2--2 of Fig. 1 and shows the joint in an enlarged view and before rolling the loop 76 flat. One Wall section 68 has flange 72 and the adjacent section 74 has a curved loop 76 surrounding flange 72. By rolling the loop 76 flat on flange 72 a tight joint is provided. If necessary the joint may be welded to insure a fluid tight joint.

The present invention can be adapted to existing storage tanks to permit storage of a greater variety of products heretofore not possible due to contamination from concrete or other materials or for other reasons.

While particular dimensions have been given in one example, these are for purpose of illustration and the invention is not to be limited thereto as diflierent sizes of tanks are contemplated. It is essential to have a shell spaced about one inch or less inwardly from the vertical outer wall of the tank, to have a water seal at the bottom of the tank and a water insoluble seal between the shell and the outer vertical wall of the tank and a surge chamber between the space between the shell and the outer tank Wall and the water seal, the surge chamber having a volume at least as big as the space between the shell and the outer tank wall.

Conventional existing methods are available for determining the water seal level by inserting a gauge stick through a manhole in the top. A water finding paste is applied to the lower end of the gauge stick which will show the depth of water since the material is inert as to the naphtha or product stored, but will change color on contact with water, thus showing directly the depth of water in the tank. The other seal liquid in space 32 can be withdrawn merely by inserting a suction pipe into the area between the concrete wall and the shell 28 when the tank is nearly empty. The level of the water insoluble seal liquid in space 32 can be checked from the top of the tank 10.

What is claimed is:

1. An apparatus including a storage tank, an inner vertical extending shell of substantially the same contour as the wall of said tank and spaced therefrom, means for securely holding said shell in position, said shell at its upper and lower ends being spaced from and out of contact with said tank, a relatively short vertical dam secured to the floor of said tank and of substantially the same contour as said tank, said vertical dam being spaced inwardly from the lower end of said shell and parallel thereto, the lower end of said shell being provided with an inverted U-shaped chamber in vertical cross section, said chamber being spaced from and straddling said vertical dam and communicating with the space between said shell and said tank and being open at its bottom portion for communication with the bottom of said tank, said chamber having a volume at least as big as the volume in the space between said shell and the wall of said tank.

2. An apparatus of the character described including a storage tank, an inner vertical shell of substantially the same configuration as the vertical wall of said storage tank and spaced therefrom a small distance, means for spacing the top and bottom of said shell from said tank, a relatively short vertical dam member secured to the floor of said tank and of substantially the same configuration as said shell, said vertical dam member being spaced inwardly from the lower end of said shell, the lower end of said inner shell being provided with an angular annular member extending inwardly therefrom to form with the lower end of said shell an inverted U-shaped chamber in vertical cross section straddling said dam member and spaced from the bottom of said tank and the top of said dam member, said U-shaped chamber acting as a surge chamber to receive sealing liquid from the space between said shell and said tank wall.

3. An apparatus of the character described according to claim 2 for storage of water-insoluble liquids wherein a liquid water seal is provided on the floor of said tank with the liquid water entering the bottom portion of said inverted U-shaped chamber but having a level below the top of said vertical dam member and a Water-insoluble sealing liquid is provided for the space between said shell and said tank wall, said water-insoluble sealing liquid having substantially the same specific gravity as the stored liquid product, said inverted U-shaped surge chamber being of a size sufficient to receive all of the water-insoluble sealing liquid upon emptying of said tank of the stored liquid.

4. An apparatus of the character described including a circular storage tank having a top, a bottom and a side wall, an inner vertical cylindrical shell spaced a small distance from the side wall of said tank and from the top and bottom of said tank, means for securing said shell in position, a relatively short vertical annular dam member spaced inwardly from said shell and secured to the bottom of said tank, the lower end of said shell being provided with an angular annular flange extending inwardly therefrom and having an annular horizontal flange portion and a vertical annular flange portion to form with the lower end of said shell an inverted U-shaped chamber in vertical cross section straddling said dam member and spaced from the bottom of said tank and the top of said dam member, said U-shaped chamber acting to receive sealing liquid from the space between said cylindrical inner shell and said tank wall upon emptying of said tank of the stored liquid.

References Cited in the file of this patent UNITED STATES PATENTS Re. 15,347 Van Rensselaer May 2, 1922 61,148 Bizard Jan. 15, 1867 1,823,256 Clark Sept. 15, 1931 2,057,248 Peyrouze Oct. 13, 1936 2,638,338 Williams May 12, 1953

Images