US2297985A

US2297985A - Floating roof

Info

Publication number: US2297985A
Application number: US266745A
Authority: US
Inventors: Rivers George
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-04-08
Filing date: 1939-04-08
Publication date: 1942-10-06
Anticipated expiration: 1959-10-06

Description

G. RIVERS FLOATING ROOF Oct. 6, 1942.

Filed April 8, 193 9 2 Sheets-Sheet l G. RIVERS FLOATING ROO F Oct. 6, 1942.

Filed April 8, 1939 2 Sheets-Sheet 2 INYENTOR. 650 949 [21106715,

Patented Oct. 6, 1942 UNITED STATES PATENT OFFICE FLOATING ROOF George Rivers, East Chicago, Ind. Application April 8, 1939, Serial No. 266,745

6 Claims.

The invention relates to tanks for storing'gasoline and other volatile liquids and has reference more particularly to an improved floating roof therefor.

An object of the invention is to provide a floatlng roof having a liquid seal for sealing the space between the said roof and the side walls of the tank.

Another object of the invention is to provide a roof which will float on the surface of the liquid in the tank so as to form a vapor space toprovide for breathing of the roof, an action resulting from'expansion and contraction of vapors given off by the liquid due to temperature variations.

A further object is to provide a vent for the floating. roof of the invention which will permit escape of thevapors from the space under the making use of the liquid in the tank.

Another object resides in the provision of guide means for guiding the floating roof as it rises and falls with changes in the level of the liquid in the tank and also in providing pontoons for said roof which will serve as roof supports when the roof is resting on the tank bottom.

With these and various other objects in view. the invention may. consistof certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodixnent of the invention and wherein like reference characters are used to designate like parts Figure 1 is a fragmentary sectional view taken through a storage tank showing the same equipped with the floatingroofof the invention;

Figure 2 is a fragmentary top plan view of th floating roof shown in Figure 1;

Figure 3 is a detail sectional view showing the construction of the liq id seal; and

means for the floating roof, to be presently described, consists of uprights in the form of rods l5 extending the height of the tank and which are suitably secured to the bottom member ID by welding as at [6. Said rods at their upper ends are tied together and to the rim of the tank by the guy wires 16 and H, the former extendirm between spaced uprights and the latter connect-' ing its particular upright with the angle member l4. Each guy wire is provided with a turnbuckle l8 for adjusting and aligning up the said uprights. I

The floating roof of the invention essentially consists of a substantially horizontal deck 20 preferably formed of j metal and imperforate throughout its circular extent except when possibly a roof drain is provided, if a dry top floating roof is desired. The deck 20 is the same shape as the tank but somewhat smaller in area so that an annular opening exists between the roof and the side walls of the tank. A depending skirt 2| extendsaround the periphery of the deck 20 and is suitably reinforced and strermthened at its lower end by the angle member 22. The said skirt also projects a short distance in an upward direction abovethe deck 20 to form a rim 23 extending around the periphery of said deck. When desired the chamber within the upper rim and above the deck may be filled with waterto act as a heat insulator against rapid temperature changes. The said rim and deck also provide supporting means for the railing, indicated in its entirety by numeral 24, and which includes the uprights 25 and cross diagonal pieces 26. The underside of the deck 20 is equipped with a plurality of pontoons 21 which are uniformly distributed over the area of the deck. In addition the depending peripheral skirt 2| is provided with shell pontoons 28, Figure 2, which in addition to strengthening said skirt, also assist the pontoons 21 in floating the roof in the liquid within the tank. A roof drain 30 may be located substantially centrallyof the deck 20 and for accommodating the uprights I5 the floating roof is provided with sleeves 3| secured to the underside of the deck as at 32 and which may be additionally secured at their lower ends by anysuitable means not shown.

The invention provides a liquid seal for sealing the space between the floating roof and the side walls of the tank. The liquid 33, Figure 3, which may be water, oil, etc., is contained in fireproof canvas-like material 34 of asbestos or the like, suitably secured to the rim 23 of the roof-and having securement at its other end to the railing 24. The material 34 is thereby suspended from the roof in a manner to form abag and which,

times.

A wearing strip 35 is located between the liquid container and the shell of the tank so as to protect the material 34 of the liquid seal which would 7 otherwise be subjected to severe wear due to the vertical movement of the roof within the tank. Said wear strip may be formed of asbestos or other canvas-like material and since the strip takes most of the wear it is obvious that the same will have to be renewed from time to time. However, the renewal of thewearing strip is a relatively simple matter as compared with the renewal of the entire liquid container and is much more economical.

The roof of the invention is'designed to float on the liquid within the tank in a manner to form a vapor space above said liquid. More particularly, the vapor space is defined by the surface of the liquid, the deck 20 and the depending peripheral skirt 2|. It will be observed that only the lower end of the depending skirt dips into the liquid and the extent to which this lower end is immersed is controlled by an adjustable vent designated in its entirety by numeral 38. The vent may be considered an adjustable blow seal since the same has operation to automatically seal itself after venting the vapor space under the deck 20 of the roof. The seal comprises a tube or pipe 40 extending through the roof deck The venting of the vapors as above described will allow the floating roof to sink further into the liquid inthe tank and eventually the U-tube will be immersed in liquid again to prevent further escape of the vapors. The same operation as above described for venting the vapor spaceis repeated should the vapor pressure reach the predetermined maximum. In the case of a vacuum condition existing within the vapor space the suction will siphon the liquid from the U- tube, permitting atmospheric pressure to prevail under the deck 20 of the floating roof. It will be observed that the discharge end 43 of the vent is at all times below the level of the liquid and therefore the vapors within .the vapor space can escape only by the operations above described.

The floating roof of the invention will float on the liquid in the tank by means of the vapor space which forms a' pontoon effect. The cubic contents of the space will vary in accordance with the length of the peripheral depending skirt 2| .;.;and-the permissible vapor pressure within the 20 and which has an open top in the form of a goose neck 4| above the deck. Below the deck the tube provides a U-shaped portion 42 adapted to contain a liquid which will seal the vapor space under normal conditions. The tube 40 is additionally provided with a portion 43 forming an open discharge end therefor, which, however, is closed at all times by the liquid within the tank since portion 43 is made long enough to extend into the liquid. The depth of the vapor space under the deck 20 is largely a matter of design of the U-shaped portion 42 of the automatic vent. The specific gravity of the liquid to be stored in the tank and the permissible vapor pressure to which the deck 20 of the roof may be subjected must also be considered.

For the operation of the floating roof it will be assumed that the tank is empty and that the roof rests on the bottom ID of the tank. For this purpose the pontoons 21 extend some distance below the peripheral skirt 2|. Said pontoons therefore serve as roof supports to hold the roof deck 20 in substantially flat position. The pontoons also protect the drain 30 and the discharge end 43 of the vent when the roof is resting on the tank bottom. At the start of the filling operation the liquid will rise within the vapor space under the roof and any vapors trapped in said space will escape through the automatic vent, it being understood that the U-shaped portion 42 is empty. The rise of liquid will continue until the said U portion is immersed, whereupon the U-tube will fill'and further escape of vapors will be prevented. Vapor pressure under the deck will build up as the filling operation continues. If for any reason the pressure becomes excessive, or in other words, exceeds a maximum pressure for the particular roof, the column of liquid in the U-tube 42 will be caused to discharge through the discharge and 43 of the vent and the vapors will accordingly escape from the open top of the vent.

same will be controlled by the design of the automatic vent including the U-tube 42. Even though the liquid may rise above the said U-tube the vapor space remaining will be sufficient to float the roof. Under such conditions the floating of the roof is further aided by the pontoons 21 and the shell pontoons 28.

The drain 30 located substantially centrally of the deck 20 at the lowest point in the same will discharge rainwater and melted snow into the liquid stored within the tank. Since the water and oil will not mix and due to the specific gravity of water, which is heavier than that of the oil, the water will settle to the bottom and 'may be drained from the tank when necessary through any valved outlet provided for the purpose. The floating roof as shown in Figure 1 is characterized by a dry top. Often due to climatic and weather conditions a water top floating roof is more suitable. This only requires that the drain 30 be closed since the space above the deck may be flooded to the depth of the rim 23.

What is claimed is:

1. A vapor seal for a floating roof including a horizontal deck and a peripheral skirt depending below the same to form with said roof a vapor space above the surface of the liquid, a tube extending through the deck and having a bent portion formed on the lower end below the deck, said bent portion simulating a U with the terminal end thereof being located a predetermined distance below the deck, and a discharge portion having connection with the other leg of said U a substantial distance above the bottom thereof, said discharge portion having communi-' cation with the tube including the terminal U thereof, and said portion depending below the bottom of the U and having its terminal end located below the level of the liquid in the tank under all conditions of operation.

2. The combination with a tank containing a liquid, of a floating roof for said tank including a horizontal deck having means depending below the deck forming a vapor space above the surface of the liquid, means carried by said deck for venting the vapor space including a venting tube extending through the deck to depend therefrom into the vapor space, the said depending section of thetube terminating in an up wardly bent portion having an open upper end and which forms a rounded bottom for the tube, a discharge portion connecting with said depending section at a point approximately horizontally aligned with the open end of the upoperation, the said legs of the U having a height wardly bent portion, said discharge portion havto maintain the vapor space at a predetermined ing communication with the depending section maximum pressure.

and with the upwardly bent portion thereof, and 5. The combination with a tank containing a said discharge portion depending fadistance be- 5 liquid, of a floating roof for said tank including low the rounded bottom so as to extend into the a horizontal deck having a peripheral skirt deliquid at all times. pending below the deck and forming therewith 3. The combination with a tank containing a a vapor space above the surface of the liquid, liquid, of a roof for said tank and a vapor space means carried by said deck for venting the vapor below the said roof and above the surface of the 10 space including a venting tube extending liquid, means carried by said roof for venting through the deck to depend therefrom intothe the vapor space to relieve the same in the event vapor space, the said depending section of, the of excessive. pressure, including a venting tube tube inoludinga'n upwardly bent portion having extending through the roof to depend there an open upperend and which forms a rounded from into the vapor space, the said depending bottom forthe tube, a dischargeportion connectsection of the venting tube terminating in a hook I 'ing with said depending section at a point apportion forming a rounded bottom and wherein" proximately horizontally aligned with the open the upwardly directed leg of the hook portion end of the upwardly bent portion, said discharge has an open end, and a discharge tube connectportion having communication with the depend ing with said depending section at a point a subing section and with the upwardly bent portion stantial distance above the rounded bottomand I thereof and depending a distance below the depending therefrom so as to extend into the rounded bottom so as to extend into the liquid I liquid at all times, said discharge tube having at all times, and said rounded bottom for the 1 communication with the depending section intube including the upwardly bent portion being cluding the hook portion thereof, whereby said located at a distance below the deck to provide hook portion of the venting tube may be filled With liquid through the open end of its upwardly particular roof. I

directed leg and which liquid may be discharged I 6. The combination with a tank containing a therefrom through the discharge tube when'an liquid, of-a floating roof for said tank including excessive pressure exists within the vapor space, a horizontaldeck having means depending-below I ofvthe liquid in the 'tank'under all conditions of 4. A vapor seal for a floating roof includinga the deck forming a vapor space above the sura vapor space of the capacity desired fonthe' horizontal deck having a depending peripheral,- face of the liquid, means forventing the vapor a skirt forming with said roof a vapor space above: T space in the event of an excessive pressure inthe surface of the liquid, a venting tube'exte'ndeluding 1 a tube depending from the deck and, ing'through the'deckto depend therefrom into' movable in 'a'vertical direction with the deck the vapor space, the depending section ofsaid 1 tube having a lower terminal-.end bent to f orm a U, one leg of said U being formed by the-de I pending section and the other 'leg. comprising end-and .the othenileg connects with the tube, an upwardly direoted. 'portion' having anyopenlgb and adischargefportion normallysealed by the end, and said dependin sectionfof the tube inliquid in the tank and having connection "with depending tube including a'sealing portion in toward andffrom the surfaceof'the liquid, said I the, form'of-a U -wherei n one leg-has an open,

e udi a disc a e portionv connecting w eref the depend n tubefiat the, connection of the said,

with above thegu, andhaving' communication 2 other Iegvvith L the, tube, said discharge portion with the depending section and the terminal end having communication. by means. of said conthereof;said'dischargeportion havinga length nection with'the 'depending'tube andwith the so thatits end will 1 terminate below the level I U.thereof;i.

GEORGE "RIVERS.