US2341548A - Container - Google Patents

Description

Feb. 15, 1944. A. H. HEINEMAN CONTAINER Filed June `9. 1941 Patented Feb. 15, 1944 CONTAINER Arnold H. Heineman, Birmingham, Ala., assignor to Chicago Bridge & Iron Company, a corporation of Illinois VApplication `Iune 9, 1941, Serial No. 397,319

(ci. sz- 1) 3 Claims.

This invention relates to a container, and more particularly to a container including means for lessening the effects on its contents of periodic temperature variations to which it is exposed.

One feature of this invention is that it provides means for lessening the temperature swings of the contents of a container exposed to temperature variations; another feature ofthis invention is that it provides an improved container for storing volatile liquids; other features and advantages of this invention will be apparent from the following specication and the drawing, in which:

Figure 1 is a partial top plan view, with a segment of the roof broken away, of a storage container embodying my invention: and Figure 2 is a transverse vertical sectional view along the line 2-'2 of Figure 1.

It is frequently desirable to lessen in so far as possible the temperature variations in the contents of a container exposed to temperature variations, one example of this being in connection with containers for storing volatile liquids, as oil or gasoline. Such containers are exposed to direct sunlight during the day, and this heat, principally edective on their roofs, tends to raise the temperature of the contents considerably; then after the sun has set the temperature of the container and its contents falls throughout the` night, to repeat the cycle the next day. This principal cycle of temperature variations is of 4 course modified by various other temporary conditions, as rainstorms, snow, or the like; but the fact remains that a storage container, particularly in dry flat country, will generally go through a temperature variation in the neighborhood of a minimum of sixty or seventy degrees to a maximum of one hundred twenty or one hundred thirty degrees each day.

Where the contents of such a container are volatile liquids such as oil or gasoline, this temperature causes undesirable loss of the contents in that part of it is vaporized and must be v'ented dining the high temperature portion of the cycle, in order to prevent undue pressures within the container.

Moreover, as the vapor recondenses during the night water vapor in the air is sometimes drawn into the container with undesirable results. Such containers, therefore, present a situation where it is highly desirable to lessen the effects of temperature variations to which they may be exposed, in order to keep the contents at as nearly uniiorm a temperature as possible; yet it is not economically justifiable -to provide refrigeration systems or other mechanism having moving parts requiring maintenance and occasioning operating costs.

I have devised an improved container which, without parts subject to wear or requiring 'power or maintenance, lessens the eifect of temperature variations. In the form of my invention disclosed herewith I provide immediately beneath the roof of a storage container a sealed chamber having the roof as the upper wall o1-` surface thereof, and partially iill the chamber with a liquid. The chamber is built to withstand substantial pressure changes and the liquid 'so chosen that part of it changes to vapor and recondenses during the cyclic temperature variations.

In the particular embodiment of my invention illustrated herewith a storage container l0, as a tank for storing oil, comprises as its principal parts a cylindrical shell II, a conical roof I2, and supporting framework. Tanks of this type are well known and commonly used, and their construction will not be further described in this regard except to say that the shell and roof comprise welded or riveted sheet metal plates and vthe general framework follows conventional practice and is designed to withstand expected stresses. It will be understood, however, that my invention can be embodied in any type of container, that shown here being merely illustrative.

A diaphragm I3 extends across the topof the container below and slightly spaced from the roof I2, This diaphragm would also be normally formed of welded or riveted sheet-metal plates. and serves to divide the interior of the container I0 into a relatively large lower storage compartment I4 and a relatively small upper compartment I5. The upper compartment is completely sealed, isolated both from the lower compartment and from outside atmosphere; and it is appropriately braced by framework so that its walls will withstand considerable changes in pressure. A's an example, it may be desired to have the pressure within the upper chamber at times only five pounds absolute per square inch, and at times twenty-five or thirty pounds absolute, so that the walls of this upper chamber must be braced to withstand ten to flfteen pounds per square inch diierential in pressure from atmospheric pres- Sure.

I then partly ll the upper chamber to a desired depth with some liquid, here indicated as I6, the pressure within the chamber and the liquid being so chosen that at least part of the liquid is vaporized during rise in temperature to which the container is exposed, within the upper limit to which such temperature goes. Since the upper chamber is sealed the vapor thus created is held therein, and when the temperature again falls this vapor recondenses into the liquid phase. The result of this change of phase is, of course, to absorb heat of vaporization as the temperature to which the container is exposed rises; and to return this heat, by condensation, as the external temperature drops. Since the principal heat input to such a container is by direct sunlight falling on its roof during the day, it will be apparent that the presence and location of this chamber serve to absorb a large amolmt of such heat and to lessen the rise in temperature of the containers contents during the day. Moreover, radiation loss of the tank at night is at least in part supplied by the heat liberated by recondensation of the vapor, so that the temperature of the contents of the container does not drop as low at nightas it otherwise would. Moreover, the eect of change of phase of the liquid is assisted by the necessity of raising the temperature of the body ot liquid in the upper chamber before any substantial amount of heat is transmitted on through to the contents of the storage chamber.

As one example, the upper chamber of the container may be iilled with water to a depth of a foot or so, it being understood that the remaining space above the water provides a cubic foot or more of vapor space for each square foot of water surface; and then the upper chamber could be evacuated before it was ilnally sealed. Under these conditions a rise in temperature of the roof from 70 F. to 120 F. would vaporize a certain percentage of water. calcul'able when the available vapor space over the water is known, it being assumed that a vacuum was drawn down to the point equivalent to the vapor pressure of water at 70 F. Moreover, heat input to the roof of the tank would raise the temperature of the body of water in the upper compartment. The result would be a considerable absorption of heat which otherwise would have been delivered to the contents of the storage chamber, so that the contents might not rise above 110 F. whereas they might otherwise, in the ordinary type of tank, have risen to 130 F. The eifect during dropping of external temperature at night, oi' course, is also to lessen the drop in temperature of its contents, the heat present in the liquid in the upper chamber, and generated by recondensation of the vapor, serving to keep the contents warmer than they otherwise would be.

This arrangement is much better than an open ilooded roof in a number of respects.l One of these is that there is no loss of water by evaporation, an impotrant factor where the storage tank is located in dry country; another factor is that this arrangement minimizes the tendency of the temperature of the contents of the tank to fall. as well as lessening the tendency for the temperature to rise-to be contrasted with an open flooded roof, where evaporation also takes place at night and the roof tends to reduce the temperature of the tank at night below that which the contents would reach; and further, the presence of the liquid load on the diaphragm enables pressures in the storage chamber of the tank to be raised higher than would otherwise be feasible, so that less vapor from the contents of the tank is lost tor a given temperature rise than would otherwise be the case.

While water is a convenient and readily obtainable liquid whith can be used in the upper 6 chamber, it is apparent that. the desired results can be increased by the use of a properly chosen refrigerant, such as a water-ammonia solution. The amount of-heat absorbed in vaporizing an 18 per cent water-ammonia solution into a cubic foot of overhead space, in going from nve pounds absolute pressure per square inch to fifteen pounds gauge pressure, would in itself be sufncient to absorb the maior part of the heat input of the sun to the roof under normal conditions,

l5 so that the depth of the refrigerant liquid would only have to be two or three inches. That is, choice of a proper refrigerant, by increasing the amount of heat absorbed and returned through vaporizatlon and recondensation, practically ob- 20 viates the necessity of any substantial layer of liquid.

While I have shown and described certain embodiments 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.

I claim:

1. A container of the character described adapted to be exposed to daily temperature variations occasioned at least in part by exposure of its roof to direct sunlight, including: a principal storage chamber; and a smaller sealed chamber extending across substantially the entire top of the storage chamber, having the roof as one wall thereof, and being designed to withstand substantial pressure changes, this chamber being adapted to contain a liquid lessening the effects of said temperature variations on the contents of the storage chamber.

2. A container of the character described adapted to be exposed to daily temperature variations occasioned at least in part by exposure of its roof to direct sunlight, including: a principal storage chamber; and a smaller sealed chamber having the roof as one wall thereof and being designed to withstand substantial pressure 0 changes, this chamber being adapted to contain a refrigerant lessening the eects of said temperature variations on the contents of the storage chamber. 3. A container of the character described for a volatile liquid, said container being adapted to be exposed to daily temperature variations occasioned at least in part by exposure of its roof to direct sunlight, including: a storage chamber for the volatile liquid, including side walls and a top; a sealed auxiliary chamber substantially covering the top of the storage chamber and exposed to the sun; and a body of volatile liquid within the auxiliary chamber, this body being of substantial depth and having an evaporation space of substantial volume thereabove. whereby liquid from said body may evaporate during the maxima of diurnal temperatures and condense during the minima, and said body of liquid will act as a heat and cold absorbent.

ARNOLD H. HEINEMAN.

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