US2297002A - Pressure container - Google Patents

Description

/o I HIIL: l fllllll Sept. 29, 1942. D. E. LARsoN 2,297,002

PRESSURE CONTAINER l Filed Feb. 8, 1941 `4 Shets-Sheet 1 mllR Jorim /c/ Eje/"507;,

Sept ,29, 1942- D. E. LARSON 2,297,002

y PRESSURE CONTNER Filed Feb. lE5, 1941 4 Sheets--Shee'fl 2 Nummmil Sept 29, '1942. D. E. LARSON 2,297,002

PRESSURE CONTAINER Sfmt-29,1942.A D. E. LARSOIQ 2,297,002

PRESSURE CONTAINER Patented Sept. 29, 1942 PRESSURE CONTAINER Donald E. Larson, Chicago, lll., assigner to Chicago Bridge & Iron Company, a corporation or nunon Application February s, 1941,- serm No. s'zaosi (ci. 22o-1) 6 Claims.

This invention relates to improvements in pressure containers and more especially to such a container particularly adapted for storing products of high value and relatively low volatility such as aviation gasoline, naphtha and the like.

Among the features of my invention is a pressure vessel which can be built economically in" large units. One of the things that adds greatly to the cost of any large vessel designed for a low Working pressure is the necessity of strengthening it to withstand the full working gas pressure when it contains little or no liquid. 4 In containers Where this is taken careI of by curved bottom plates, circular girders, or inclined tension members, or combinations of the same, the con' struction becomes quite expensive.

I have found that if enough weight can be hung on the shell at the equator and on the roof at the intersections or cusps, the columns can be made vertical and the bottom substantially flat, thus Veffecting an appreciable saving in cost. In the following specication I have shown how this can be accomplished inseveral practical ways.

In those forms of device embodying the features of my invention illustrated in the accompanying drawings, Fig. 1 is a top plan view; Fig. 2 is a. vertical sectional view; Figs. 3, 4 and 5 are diagrammatic views similar to Fig. 2 showing modied forms; Fig. 6 is a View showing general relations and computations; and Figs. 7, 8, 9 and 10 are diagrammatic views similar to Fig. 2 showing modified forms.

As shown in the drawings, the container of' Figs. 1 and 2 is circular in horizontal cross-section and provided with a noded roof IB, cylindrical shell II and vertical columns I2. The central portion of the bottom as indicated by I3 is flat. The outer periphery of the bottom is in the form of a trough I3a. I4 indicates a dam at the inner edge of the trough I3a. The central portion of the top as indicated by Ilia is dome shaped and the outer periphery is noded as indicated by Illb. The line ofintersection of the portion Illb with-the periphery of the central dome II'Ia, or cusp, is indicated by I5.,

I6 indicates the inlet pipe so that all incoming liquid is directed into the outer trough I3a. Itis confined there by the dam I4 which serves both as a retainer and as a girder'for transmitting load to the tension ties I2a in the outer post circle. After the trough has become full, the liquid ilows over the dam I4 and thereafter the entire tank is lled to the normal maximum level which for example may be the line I5.

When the tank is Aempty it is designed to operate at a pressure of say 1A pound per square inch which is not great enough to cause any part of the structure to lift off of the foundation. After the trough I3a has been filled to the top of the dam I4, the vessel can operate at full working pressure throughout the remainder of its capacity range.

For example, the full working pressure may be 1 pound. In order to insure the Y- presence of liquid in the trough I3a before permittingv full Working pressure, the auxiliary pressure vent Il is provided. It is not necessary to show the details oi this vent. It will suiilce to say that it is connected to the interior of the tank by the pipe I8, the lower end I8a of which is a short distance below the upper edge of the dam I4. The valve Il is set to vent at say A pound per square inch pressure, Consequently, whenever there is no liquid in the pipe I8, the tank will vent at 1/4 pound. Therefore. the tank will vent at this pressure until the trough I3a is filled when liquid will enter the pipe I8` through the lower end Ilia to shut oil the vent Il. I9 is a regular or main vent which has a pressure valve adapted to vent at the full working pressure which may,for example, be l pound per square inch. 20 indicates a vacuum valve set to vent inwardly at any desired negative internal pressure. -For example, this valve may vent whenever the internal pressure becomes 1 ounce or more below atmospheric pressure.

The average depth of liquid in the trough I3a required to develop the fullworking pressure is determined by the following considerations. The weight of liquid in the trough plus the force of the specied working pressure, acting downwardly on its surface must equal the product of the working pressure and the cross-sectional area of the tank. The low point of the trough must be so located that the weight of the liquid in the trough will be distributed between the shell and the outer circle ties in the correct proportion to 'balance the uplift at these point-s caused bythe gas pressure acting on the roof.

In Fig. 6 I have shown the method'of computing dimensions and proportions. In this drawing 1' :tank radius in feet.

in feet.

VA:uplift at shell in pounds per foot. VCL-.uplift at cusp in pounds per foot. f H :height of liquid to balance uplift in fee't.

.e -=distance from-center line to trough bottom.

:weight of liquid in pounds per cubic foot.

.As an example it may be assumed that it is desired to build an 80,000 barrel tank with an over- 45(3600 1600) liquid in trough 40 49.8 feet from centerline t Z 60 V 7200- 1600: bottom of trough It is to be noted that when r-l-a: Slt-0.681) T 20a indicates the outlet pipe. Liquid is withdrawn from the center portion thus insuring that the outer trough remains full until the last of the liquid is removed.

An 80,000 barrel 11/2 pound pressure tank, 120 feet in diameter. as described above,.would re quire about 4 feet of gasoline in the outer trough or about 4,500 barrels to develop the full working pressure. The tank would operate as a 54 pound pressure tank from capacity to 4,500 barrels and have a 11/2 pound pressure tank from 4,500 barrels to 80,000 barrels. has the distinct advantages that the gauging problem is simplified and all of the stresses are statically determined. About 70% of the weight of the tank is plain tank construction. No trusses or other highly fabricated parts are required. A distinct saving in fabrication and erection costs is eiected.

It will be seen that the liquid confined in the outer troughl serves to counterbalance the uplift due to gas pressure.

In the device of Figs. 1 and 2 the bottom of the outer trough is dished" or curved downwardly. This trough could also be made flat as shown in Figs. 3 and 5 by merely extending the central portion of the flat bottom. In such cases, however, the bottom of the trough should be stiiiened by radial trusses or girders as indicated by 330 and 530. In theseviews the dam or retainer plate corresponding to |4 in Fig. 2 is indicated by 3M and 5|4, respectively, and the bottom by 3|3 and 5|3. The extension of the at bottom forming the at bottom of the trough is correspondingly indicated by 3|3a and 5|3a.

In the device of Figs. 1 and 2 the side wall or shell of the tank is cylindrical. This construction is also employed in the device of Fig. 3 where such side wall is indicated by 3H. In the devices of Figs. 4 and 5, however, the side wall as indicated by 4|| and 5| I, respectively, is curved from the top entirelyto the bottom. In the device of Fig. 4 this construction is shown in combination with a truss, the bottom of which is curved or dished as indicated by 4|3a the same as the trough of the device of Fig. 2.

It will be seen that in each case the top of the A tank of this type tank has a central domed portion surrounded by a domed or upwardly curved peripheral portion over the peripheral trough in the bottom. 'Ihe central domed portion of the roof is joined tothe domed peripheral portion by the cusp I5, 3|5, H5 or 5| 5. In each case the weight of liquid in the peripheral trough at the bottom serves to exert a downward pull at the periphery of the central domed portion of the roof through the posts or tension members |2a, 3|2a, 4|2a, or

5|2a, and also exerts a downward Dull on the equator of the tank; that is the shell or side walls ||,3||, 4H, or 5H. Y

In Figs. 7, 8., 9 and 10 I have'shown diagrammatically other means for imposing a. downward pull on the side wall of the tank to counterbalance, ,at least partially, upward gas pressure within the tank. This downwardpull on the side wall is transmitted to the periphery of the central domed portion. For example, in these figures the central domed portion is indicated by 1 Illa, 8|0a, 9|0a and Illa, respectively. The side walls are indicated by 8||, 9ll'and |0||, respectively. As shown in Fig. '7, tension' members 1| Ia are provided at intervals* around the tank with their upper endsattachedto the sidewall and their lower ends anchored in a concrete ring '|I3a. The construction of Fig. 8 is similar except that the side wall itself is' continued downwardly as indicated by 8| la to the ground level where it is anchored by means of the anchors 850 to the concrete ring 8|3a. In the device of Fig. 9 triangular plates 9| a fasten-the vside wall to the torus 950 suitably Weighted with concrete or other appropriate material. In the device of Fig. 10 the side wall is anchored by means of the hollow torus |0| la filled with suitable liquid |05|l The invention is particularly applicable in connection with a pressure container having a fiat bottom. In a container of this kind, internal pressure tends to bend the edge of a fiat bottom upwardly. 'I'his tendency is caused by the 'connection of the periphery of the roof to the edge of the bottom either through the side 'wall o'f the container or other tension members. The upward pressure on the roof operating through the side wall or these other tension members tends to bend or cunve the edge of a flat bottom upwardly. In the practice oct my invention I provide a trough attached to the periphery ofthe roof, with liquid in it, the -weight of the liquid serving to counteract or counterbalance this upward pull and thus prevent the edge of the flat bottom from curving or bending upwardly. In the construction shown in Fig. 2 it 'will abe seen thatA the trough |3a is connected to the periphery of the roof by both the tension members |2a and the side lwall WhileI have shown and described certain em- I bodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my intention to claim all novelty inherent in :my invention as broadly as permissible, in view of the prior art.

What I claim as new, and' desire to secure .by Letters Patent, is:

1. In combination with a pressure container having a flat bottom and domed top, a .peripheral trough attached to the periphery of the top and communicating with the interior of the container, said atachment joining the trough to the periphery of the top in supporting relation with respect to the top so that the weight of the trough with liquid therein tends to prevent upward movement of the periphery of the top from internal pressure in the container, said trough being supported by means other than said attachment to the periphery of the 'top when there is no internal pressure in the container, and liquid in the trough, the weight of said liquid serving to prevent upward bending of the periphery of the bottom from internal pressure.

2. In combination with a pressure container having a fiat bottom and domed top, a peripheral trough outside oi the periphery of the bottom and attached to the periphery of the top and communicating with the interior of the container, said attachment joining the trough to the periphery of the top in supporting relation with respect to the top so vthat the weight of the trough with liquid therein tends to prevent upward movement of the periphery of the top from internal pressure in the container, said trough being supported by means other than said attachment to the peri-phery of the top when there is no internal pressure in the container, and liquid in the trough, the weight of said liquid, serving to prevent upward the inner edge of the trough is attached to-the periphery of the top by tension members and in which the outer edge of the trough is attached to the periphery of the top by the side wall` of.

the tank andan outer peripheral top portion.

4. A container as claimed in claim 1 in which the inner edge of the trough is attached to the periphery of the top by tension members and in which the outer edge of the trough is attached to the periphery of the top by `the side wall of the tank and an outer lperipheral top portion, said outer peripheral top portion joining the main top portion by a cusp.

45. Acontainer as claimed in claim 1 with an inlet pipe leading to the trough and an outlet pipe leading from the bottom of the `tank inside the inner circumferenceof the trough. l

6. A container as claimed in claim 2 with an inlet pipe leading to the trough and an outlet pipe leading from the bottom of the tank inside the inner circumference of the trough.

DONALD E. LARSON.

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