US2360692A - Counterbalancing means for expansion roofs - Google Patents

Description

Oct. 17, 1944i 7 T. b. LARSEN 2,360,692

COUNTERBALANCING MEANS FOR EXPANSION ROOFS Filed Aug. 14, 1941 2 Sheets-Sheet 1 INVENTOR. Q Q BY 0 Aarzserz Q Oct. 17, 1944. T, o. LARSEN 2,360,692

COUNTERBALANCING MEANS FOR EXPANSION 'ROOFS Filed Aug. 14, 1941 2 Sheets-Sheet 2 INVENTOR.

J "6 0; lar'aen/ BY @r/ Patented Oct. 17, 1944 UNITED STATES PATENT OFFICE COUNTERBALANCIN G MEANS FOR EXPANSION ROOFS Thyge O. Larsen, Hammond, Ind., assignor to Graver Tank & Mfg. 00., Inc., Catasauqua, Pa... a corporation of Delaware Application August 14, 1941, Serial No. 406,837

8 Claims. (01. 48176) The invention relates to storage tanks for' storing either gases or vapors or volatile liquids and the vapors arising therefrom and has reference more particularly to improved counterbalancing means for the expansion type of roof as shown in the patent to Phillip S. Graver No. 2,277,398, granted March 24, 1942, and entitled Expansion roof for oil storage tanks.

In the type of tank above referred to, the roof in moving vertically upward provides increased vapor space for the expanding gases and vapors. Said gases and vapors expand during the heat of the day and unless they are Withdrawn from the tank or additional space within the tank is provided they produce a serious increase in pressure on the roof of the tank. When the tank is storing volatile liquids additional vapors are produced during the day as a result of evaporation. However, if these vapors are conserved they can be reclaimed during the night owing to the cooler night temperature which condenses the vapors. The production of vapors during the day followed by subsequent cooling and con- (lensing of the vaporsduring the night is known as .breathing and inlarge tanks, particularly if only partly filled, such breathing will be substantial. I

It is well known that severe evaporation losses will result during the storing of volatile liquids such as gasoline or the like if the vapors are expelled to the atmosphere in order to relieve the pressure within the tank. Therefore, as a matter of economy it is necessary to conserve the vapors so that they can be eventually condensed without any loss of the valuable fractions. For these and other reasons it is desirable to equip oil storage tanks with an expansion roof capable of considerable movement in a vertical direction to vary the vapor space within the tank. Thus in expansion roof tanks it is not necessary .to discharge any vapors to the atmosphere even under the most severe breathing conditions.

Greater possibilities are offered when an expansion roof tank is connected to a number of existing old tanks providing breathing space therefor. Since it is not practicable to reinforce the roofs of the old tanks the invention provides counterbalancing means for expansion roof tanks whereby the effective pressure for operating the same can be made to conformto a safe pressure for the old tanks.

Therefore an object of the invention is to provide novel counter-balancing means forexpansion roof tanks whereby the rool can be operated at any desired pressure below that caused by the actual weight of the roof. 7

Another object of the invention is to provide improved counter-balancing means for expansion roof tanks wherein the effective weight of the counter-balancewill not vary even though the tank may be partly full of liquid or, substantially empty.

A further object of the invention is to provide counterbalancing means for a movable roof which in additionto its counter-balancing function will have operation to maintain the roof substantially horizontal during vertical movement thereof.

With these .and various other objects in view,

the invention .may consist of 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 embodivment of the invention and wherein like reference characters are used to designate like parts- Figure 1 isa view illustrating one embodiment of the invention with the tank beingshown in section and with the roof in deflated position,

which locates the counter-balance in its upperthe center column of the tank and positioned concentrically within a retaining well therefor.

Referring more in detail to the drawings, particularly Figure l, the expansion roof tank selected for illustrating the invention includes side walls 10, a bottom wall H adapted to rest on the earth or other suitable support and a supporting structure including a center post [2 hav- I! is provided so that the weight on the center post will be more evenly distributed to the ground. The cylindrical walls Ill of the tank are suitably reinforced at their upper end by means of inwardly directed shell girders, to be more particularly described, which provide guiding means for posts depending from the expansion roof and supporting means for the sheaves having contact with flexible cables. I

The present tank is provided with an outside launder l8, which is best shown in Figure 2. The base of the launder is formed by the angle piece 20 extending around the circumference of the tank, the same having a reinforcing part 2| associated therewith and which forms the base proper of the launder. Upstanding plate members 22 and 23 have securement to each other and to the angle 20 so as to form the launder with the cylindrical wall of the tank and which in effect provides a trough for containing a liquid such as gasoline or oil to form a seal with respect to the bell holder type of roof. Members 22 and 23 are reinforced at their upper end by outwardly directed angle pieces 24 and 25.

The open top tank so far described is closed by means of a movable roof in the form of a holder bell so as to provide for the necessary expansion in the event of increased pressure on the part of the gases or vapors housed within the tank. The movable roof in the form of a holder bell is indicated in its entirety by numeral 26, the same having telescoping relation with respect to the upper portion of the cylindrical wall III.

The bell includes a cambered roof 2'! having,

a depending skirt 28 for location within the launder and also having a depending rain shed skirt 30 which forms a cover for the launder, protecting the same from the weather. The rain shed skirt is concentric with skirt 28 and the same is suitably secured to the outer periphery of the roof by the angle 3|, Figure 2, which in turn is secured to a horizontally disposed outer extending rafters 36, Figure 1, which unite at the apex of the roof, being securely joined to the center piece 31 which rests on the cap l3 when the movable roof is in deflated position.

Depending post 38 are provided for guiding and controlling the vertical movements of the.

holder bell including the cambered roof 2'! and the depending skirt 28. The posts are suitably fastened to the roof by means of the plates 35 to which the upper end of each post is respectively welded as at 39. The posts depend vertically downward, passing through openings pro.

vided therefor in the inwardly extending shell and down movement and particularly to guide .75

the post and partly anchor the lower end thereof when the roof is fully inflated. The bracket 43, located below the rollers, provides a support for journalling at its outer end the sheave 44 which has contact wtih a flexible cable or chain 45 extending around said sheave and travelling downward in parallel relation with the post, being fixed to the lower end thereof by means of connection 46. Two brackets 43 are provided for each sheave and which are located on the respective sides of the post, being welded at their inner ends to the cylindrical wall Id of the tank and at their outer end to the uprights 4'5. Uprights 41 are in turn supported by the shell girder 48 having an opening 49 therethrough to permit passage of the post and its chain connection 46. A similar shell girder 56 is located immediately below 48, the same likewise having an opening 5| for accommodating said post. The last shell girder 52 is suitably secured to the inner walls of the tank in substantial horizontal alignment with the base of the launder. The shell girder at this point help to reinforce the tank and the same also provides supporting means for the depending collar 53 which provides an opening of suflicient size to accommodate the post and chain connection 46. The posts are spaced circumferentially around the inside of the tank and the various girders above defined have openings as described for accommodating a post. As shown in Figure 2 the roof is in deflated position and accordingly the depending skirt 28 extends substantially to the bottom of the launder and each depending post 38 extends through the lowermost sheave 52 through collar 53 thereof for a short distance below said collar, all as shown in said figure.

During vertical movement of the expansion roof herein disclosed it Will be seen that the depending posts 38 are guided by the rollers 4| which facilitate movement and thereby maintain the roof horizontally disposed. In addition to being guided by the rollers certain depending posts have connection with cable means such as 45 in the form of a flexible cable or chain. As previously explained, the chain connects with the extreme lower end of its respective depending post as at 46, the post having a plate 54 welded thereto for the purpose. The chain extends substantially parallel with its post and passes over the sheave 4-4 suitably journalled adjacent the post by the sheave bracket 43. In accordance with the invention the several chains 45 from the circumferentially positioned posts 38 have connection with counterbalancing means which act in a direction to facilitate upward movement of the expansion roof. Thus by counter-balancing the weight of the roof the same will operate at a pressure considerably below the pressure which would otherwise be require-d.

Each flexible chain 45 extends radially inward toward the center post [2, having a turnbuckle 55 interposed in its length for purposes of adjustmenuand passes over a sheave 56 which directs the flexible chain downwardly in parallel relation with the center post 12. Each of the sheaves 56 is suitably journalled by brackets 51 secured to the center post. The flexible chains 45 extend from the sheaves 56 almost to the base of the center post where said chains connect with a. substantially circular counter-weight 58. Connection between the chains and the counterweight may be effected by the eyelets 59 embedded in the counter-weight and to which the chains are secured. Since the depending posts 38; are circumierentially' disposed around the interior of the tank itwill be understood that the brackets 51 and sheave 56 will extend radially from the center post l2,'ha.Vlng substantial alignment with their respective depending post. The counterweight 58' will also have connection at circumferentially spaced points with the flexible chains. Said counter-weight has a substantiallysquare center opening 60 for receiving the center post and for purposes to be presently described the counter-weight is positioned within a cylindrical wellformed by the circular member 6|; Said member extends vertically upward from the bottom wall H, being welded thereto so that the well will contain a quantity of liquid such as gasoline or oil. -When the expansion roof is in deflated position, such as shown in Figure 1, in which position the roof is supported by the center postl2 and by the cylindrical walls ID of the tank, it will be understood that the counterweight is located'in its uppermost position. The action of the counter-weight is imparted through the flexible chainsto the depending posts and which is in a direction to urge said posts and thus the roof to move vertically upward. By selecting a counter-Weight of proper weight for the particular roof associated therewith the roof can be made to operate at very low vapor pressures.

It is of course necessary that the effective action of the counter-weight 58 remain constant, irrespective of whether the tank is full of liquid or empty. When the counter-weight is immersed in a liquid its action is reduced to a certain extent due to' the'buoyant effect of the liquid thereon. Were it not for the well 6|, which retains a quantity of liquid for the counter-weight its effective action would be entirely different for an empty tank in comparison to a tank containing some liquid. Therefore the action of the well is to' maintain the counter-weight submerged at all times and'its action is therefore independent of the existing oil storage capacity of the tank.

During operation of the expansion roof it will' be understood that the launder l8 will contain oil or water as a sealing mediumfor the depending skirt 28. The tankmay also contain oil, in which case the movable roofwill be subjected to varying vapor pressures. The action of the counter-weight 58 is to materially lessen the weight of the holder bell 26 including that of the posts 38 depending therefrom. Thus at a predetermined vapor pressure the roof willrise to increase the space within the tank. When the present tank is connected to oil storage tanks so as to relieve the pressures on the roofs thereof the vapors and gases are conducted to and from the conduit 62. As a result of the counterweight for the expansion tank the movable roof can be adjusted to rise at vapor pressures which are safe pressures for the oil storage tanks.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will of course be apparent to those skilled in the art without de' parting from the spirit of the invention or the scope of the claims.

What is claimed is:

1. A storage tank comprising a substantially cylindrical shell, a vertically movable roof, sealing means between the shell and the roof whereby the roof may move vertically with respect thereto to vary the vapor space within'the tank, guiding means for guiding the roof in its vertical movements including posts depending from thereof and having location within the tank, counterbalancing meansfor said roof including a movable counter-weight, and flexible means connecting the counter-weight with eachdepending post respectively at the lower end thereof and in a. manner to exert an upwardforce on each depending post, the weightof the counter-weight being such that the sumof'the upward forces exerted on the depending posts is equal to 'or less than the weight of the roof, whereby relatively low pressures within the vapor space will cause vertical movement of the roof.

2. A storage tank comprising a substantially cylindrical shell, a vertically movable roof, sealing means between the shell and the roof whereby the roof may move vertically with respect thereto to vary the vapor space within the tank, guiding means for guiding the roof in its vertical movements includin posts depending fromthe roof and having location within the tank, rollers supported from said cylindrical shell and having contact with the depending posts respectively for guiding the same during said vertical movement, counter-balancing means for said roof including a movable counter-weight having flexible means connecting the counter-weight with each 'depending post at the lower end thereof and in a manner to exert an upward force on each depending post, the weight of the counter-weight being such' that the sum of the upward forces exerted on the depending posts is equal to or less than the weight of the roof, whereby relatively low pressures within the vapor space will cause vertical movement of the roof, and sheaves having contact with each said flexible. means intermediate the ends thereof.

3. A storage tank comprising a substantially cylindrical shell, a vertically movable roof, sealing means between the shell and the roof whereby movements including posts depending from the a roof and having location within the tank, rollers supported from saidrcylindrical shell and having contact with the depending posts respectively for guiding the same during said vertical movement, counter-balancing means for said roof in.- cluding a movable counter-weight having flexible means connecting the counter-weight with each depending post at the lower end thereof and in a manner to exert an upward force on each depending post, the weight of the counter-weight being such that the sum of the upward forces exerted on the depending posts is equal to or less than the weight of the roof, whereby relatively low pressures within the vapor space will cause vertical movement of the roof, and sheaves having contact with each said flexible means intermediate the ends thereof, certain of said sheaves being supported from the cylindrical shell of the tank.

4. In a storage container for gas or liquid, in combination, an open top tank, an expansion roof for said tank movable with respect thereto to vary the vapor space within the tank, means providing a seal between the tank and roof so as to confine vapors within the tank, a plurality of posts fixed to the roof at circumferentially spaced points and depending within the tank, a center supporting column within the tank for centrally sup orting the roof in deflated position, a counter-balancing weight for said roof having encircling relation with saidcenter supporting column, and flexible meansconnecting the counterbalancing weight with certain of said depending posts respectively at the lower end thereof and in a manner to exert an upward force on each depending post, the weight of the counter-weight being such that the sum of the upward forces exerted on the depending posts is equal to or less than the weight of the roof, whereby relatively low pressures within the vapor space will cause vertical movement of the roof.

5. In a storage container for gas or liquid, in combination, an open top tank, an expansion roof for said tank movable with respect thereto to vary the vapor space within the tank, means providing a seal between the tank and roof so as to confine vapors within the tank, a plurality of posts fixed to the roof at circumferent'ially spaced points and depending within the tank, a center supporting column within the tank for centrally supporting the roof in deflated position, means for counter-balancing the weight of said movable roof to facilitate upward movement thereof including a counter-weight having encircling relation with the center supporting column, flexible means connecting the counter-weight with each depending post respectively at the lower end thereof, and sheaves having contact with each said flexible means, the weight of the counterweight being such that the sum of the upward forces exerted on the depending posts is equal to or less than the weight of the roof.

6. In a storage container for gas or liquid, in combination, an open top tank, an expansion roof for said tank movable with respect thereto to vary the vapor space within the tank, means providing a seal between the tank and roof so as to confine vapors within the tank, a plurality of posts fixed to the roof at circumferentiallyspaced points and depending within the tank, a, center supporting column within the tank for centrally supporting the roof in deflated position, means for counter-balancing the weight of said movable roof to'facilltate upward movement thereof including a counterweight having encircling relation with the center supporting column, flexible means connecting the counter-Weight with each depending post respectively at the lower end thereof, and sheaves having contact with each said flexible means, certain of said sheaves being supported from the cylindrical shell of the tank, and other sheaves being supported from the center supporting column, the weight of said counterweight being such that the sum of the upward forces exerted on the depending posts is equal to I or less than the weight of the roof.

V 7. In a storage container for gas or liquid, in combination, an open top tank, an expansion roof for said tank movable with respect thereto to vary the vapor space within the tank, means providing a seal between the tank and roof so as to confine vapors within the tank, a plurality of posts fixed to the roof at circumferentially spaced points and depending within the tank, means having rolling contact with each post for guiding the posts in their vertical movements, a sheave positioned adjacent each'post and located near the upper end of the open top tank, a center supporting column located within the tank for centrally supporting the roof in deflated position, a plurality of sheaves supported by said center column, counter-balancing means for the roof including a counter-weight having encircling relation with said center column, and flexible means connecting the counter-weight with each depending post respectively at the lower end thereof, each said flexible means passing over one of the sheaves supported by the column and having contact with the sheave adjacent its particular depending post, the weight of said counter-weight being such that the sum of the upward forces exerted on the depending posts is equal to or less than the weight of the roof.

8. In a storage container for gas or liquid, in combination with an open top tank, an expansion roof for said tank movable with respect thereto to vary the vapor space within the tank, means providing a seal between the tank and roof so as to confine vapors within the tank, a plurality of posts fixed to the roof at circumferentially spaced points and depending within the tank, a center supporting column within the tank for centrally supporting the roof in deflated position, a counter-balancing weight for said roof having encircling relation with said center supporting column, flexible means connecting the counter-balancing weight with certain of said depending posts respectively at the lower end thereof and in a manner to exert an upward force on each depending post, the weight of the counter-weight being such that the sum of the upward forces exerted on the depending posts is equal to or less than the weight of the roof, whereby relatively low pressures within the vapor space will cause vertical movement of the roof, a well provided at the base of the center supporting column in surrounding relation therewith, and a liquid in said well for immersing the counter-weight whereby its effective counter-balancing action is substantially uniform irrespective of the quantity of liquid stored within the tank.

THYGE o. LARSEN

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