Patent Application
20160031637
This section is intended to provide background information to facilitate a better understanding of various technologies described herein. As the section's title implies, this is a discussion of related art. That such art is related in no way implies that it is prior art. The related art may or may not be prior art. It should therefore be understood that the statements in this section are to be read in this light, and not as admissions of prior art.
Liquid products, such as petroleum-based liquids, may be stored in large, substantially cylindrical storage tanks. In one scenario, a storage tank may use a floating roof, where the floating roof may have an outer diameter that is smaller in size than an inner diameter of the storage tank. The annular space between the floating roof and the inner walls of the storage tank may be referred to as a rim space. In some scenarios, a liquid product stored in such a storage tank may suffer from evaporative losses due to vapors escaping from the rim space.
Described herein are implementations of various technologies relating to a floating roof seal. In one implementation, a seal assembly for use in a storage tank may include a shoe seal configured to engage with a floating roof disposed in the storage tank and configured to be positioned in a rim space of the storage tank, the shoe seal having a shoe plate configured to slidably engage an inner diameter of the storage tank. The seal assembly may also include a liquid-mounted seal coupled to the shoe plate and configured to be disposed between the shoe plate and the floating roof, where the shoe plate is configured to shield the liquid-mounted seal from the inner diameter of the storage tank.
In another implementation, a method for forming a seal assembly for use in a storage tank may include coupling a liquid-mounted seal to a shoe plate of a shoe seal. The method may also include coupling the shoe seal to an outer diameter of a floating roof disposed in the storage tank. The liquid-mounted seal may be disposed between the shoe plate and the outer diameter of the floating roof. The shoe plate may be configured to slidably engage an inner diameter of the storage tank and to shield the liquid-mounted seal from the inner diameter of the storage tank.
In yet another implementation, a seal assembly for use in a storage tank may include a liquid-mounted seal configured to engage with a floating roof disposed in the storage tank and configured to be positioned in a rim space of the storage tank. The liquid-mounted seal may include a binding comb surrounded by a cover.
The above referenced summary section is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description section. The summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.
Implementations of various techniques will hereafter be described with reference to the accompanying drawings. It should be understood, however, that the accompanying drawings illustrate only the various implementations described herein and are not meant to limit the scope of various techniques described herein.
Various implementations directed to a floating roof seal will now be described in the following paragraphs with reference to
As noted above, large, substantially cylindrical storage tanks may be used to store liquid products. Each storage tank may use a floating roof, with the floating roof having an outer diameter that is less than an inner diameter of the storage tank. In particular, the inner diameter of the storage tank may be defined by the inner walls of the storage tank. A rim space may be formed in the storage tank, where the rim space is defined as the annular space formed between the outer diameter of the floating roof and the inner diameter of the storage tank. In one implementation, the difference between the outer diameter of the floating roof and the inner diameter of the storage tank may range from four to sixteen inches.
For example,
The floating roof 20 may be configured to move within the rim space 30 in a horizontal direction as it sits atop the liquid product 40. Thus, the size of the rim space 30 may vary depending on the position of the floating roof 20 within the storage tank 50. Further, the floating roof 20 may traverse in an upward or downward direction as the height of the liquid product 40 within the tank 50 varies due to an increase or decrease in liquid product volume. In another implementation, one or more pontoons 60 may be coupled to the outer diameter 80 of the floating roof 20.
In order to minimize evaporative emissions of the liquid product 40 from the rim space 30, one or more seal assemblies may be used, as further described below.
A seal assembly for use in the rim space 30 may be composed of a combination of a liquid-mounted seal and a mechanical shoe seal.
The seal assembly 200 may be mounted to an outer diameter 102 of the floating roof 100 within the storage tank 150. In one implementation, one or more pontoons may be coupled to the outer diameter 102 of the floating roof 100. The floating roof 100 may be set off from an inner diameter 152 of the storage tank 150 to form a rim space 120.
The seal assembly 200 may allow the floating roof 100 to move in a horizontal direction as it sits atop a liquid product (not pictured) stored in the storage tank 150. In addition, the seal assembly 200 may be configured to move with the floating roof 100 as the roof rises or falls due to changes in liquid product volume in the storage tank 150.
In one implementation, in order to minimize evaporative emissions from the liquid product, a plurality of seal assemblies 200 may be mounted to the floating roof 100 in the rim space 120. The plurality of seal assemblies 200 may each include a shoe seal 210 and a liquid-mounted seal 250, as further described below.
The shoe seal 210 may be implemented using any configuration known to those skilled in the art. In one implementation, the shoe seal 210 may include a base member 212, an adjustable arm assembly 220, a shoe plate 230, and a vapor barrier 240.
The base member 212 may be substantially vertical and may be securely coupled to the outer diameter 102 of the floating roof 100. The adjustable arm assembly 220 may be coupled to the base member 212 (as further described below), and may span the length of the rim space 120. The adjustable arm assembly 220 may also extend outwardly from the base member 212, and may be coupled to the shoe plate 230 (as further described below). The adjustable arm assembly 220 may be coupled to the base member 212 and/or the shoe plate 230 using screws, bolts, or any other fastening means known to those skilled in the art.
The adjustable arm assembly 220 may be biased in an outward direction away from the floating roof 100, such that, as a result, the shoe plate 230 is biased against the inner diameter 152 of the storage tank 150. The adjustable arm assembly 220 may be biased in the outward direction away from the floating roof 100 through the use of springs, tension joints, or any other biasing means known to those skilled in the art. The adjustable arm assembly 220 may also be configured to allow the floating roof 100 to move in the horizontal direction within the storage tank 150, as further described below.
The adjustable arm assembly 220 may be implemented using any configuration known to those skilled in the art. For example, as shown in
The first pantograph arm 213 may have a first end 214 coupled to the base member 212 through a hinging mechanism 221. In particular, the first pantograph may be configured to pivot about the hinging mechanism 221. The first pantograph arm 213 may also have a second end 215 coupled to a lower flange 222 using a hinging mechanism 223. The lower flange 222 may extend from an inner diameter of the shoe plate 230, and may allow the first pantograph arm 213 to pivot about the hinging mechanism 223. The hinging mechanisms 223 and 221 may be similar to the hinging mechanism 229 described above. The first pantograph arm 213 may also be coupled to the base member 212 and the lower flange 222 such that its first end 214 is positioned higher than its second end 215.
Similarly, the second pantograph arm 216 may have a first end 218 coupled to the base member 212 through a hinging mechanism 219, and may have a second end 217 coupled to an upper flange 224 using a hinging mechanism 225. The upper flange 224 may be positioned higher on the inner diameter of the shoe plate 230 than the lower flange 222. The second pantograph arm 216 may also be coupled to the base member 212 and the upper flange 224 such that its first end 218 is positioned lower than its second end 217.
The hinging mechanisms 219 and 225 may also be similar to the hinging mechanism 229 described above, where the second pantograph arm 216 is able to pivot about each hinging mechanism. In another implementation, the first end 218 of the second pantograph arm 216 may be coupled to the base member 212 using a pin and slot arrangement, where the first end 218 is coupled to a slot 233 of the base member 212 via the hinging mechanism 219. The pin and slot arrangement may allow for vertical movement of the first end 218 relative to the floating roof 100.
Such a pantograph assembly may be configured to allow the pantograph arms 213 and 216 to rotate relative to one another, thereby allowing the pantograph assembly to compress or decompress based on the horizontal movement of the floating roof 100. Accordingly, the adjustable arm assembly 220 as shown in
As mentioned above, the adjustable arm assembly 220 may be biased in an outward direction from the floating roof 100, thereby biasing the shoe plate 230 against the inner diameter 152 of the storage tank 150. The shoe plate 230 may be slidably engaged with the inner diameter 152, allowing the shoe plate 230 to move vertically along the inner wall as the floating roof 100 rises and falls with changing volume of the liquid product in the storage tank 150, while also maintaining constant contact with the inner diameter 152. Thus, the shoe seal 210 as a whole may be configured to move with the floating roof 100 as the floating roof 100 rises or falls with the liquid product in the storage tank 150. The shoe plate 230 may also be engaged with the inner diameter 152 such that substantially little evaporative emissions may pass between the two.
The shoe plate 230 has an upper end and a lower end, where each may be bent radially inwards in a direction away from the inner diameter 152. Such bending of the ends may facilitate movement of the shoe plate 230 over imperfections on the inner diameter 152. A portion of the shoe plate 230 may also extend below into the liquid product. The shoe plate 230 may be constructed from stainless steel or any other material known to those skilled in the art. In one implementation, the shoe plate 230 may be thirty inches in height in a vertical direction and may be 1/16 inches thick.
The shoe seal 210 may also include a vapor barrier 240 mounted between the shoe plate 230 and the base member 212, sealing at least the area between the shoe plate 230 and the floating roof 100 in order to minimize evaporative emissions from the rim space 120. In particular, the vapor barrier 240 may be coupled to the inner diameter of the shoe plate 230. The vapor barrier 240 may be composed of fabric or any other material known to those skilled in the art. The vapor barrier 240 may span the length of the rim space 120, and may be flexible to allow for horizontal movement of the floating roof 100. The vapor barrier may be coupled to the shoe plate 230 and/or the base member 212 using bolts, screws, or any other fastening means known to those skilled in the art.
When a plurality of seal assemblies 200 are used in the storage tank 150, the plurality of shoe plates 230 may be positioned next to one another along the circumference of the inner diameter 152 of the storage tank 150. In one implementation, the shoe plates 230 may be positioned along the inner diameter 152 such that substantially little evaporative emissions may pass between the plates. In such an implementation, the shoe plates 230 may form a ring of plates along the inner diameter 152. In a further implementation, a plurality of vapor barriers 240 may also be used to seal the rim space 120 around the floating roof 100.
One or more liquid-mounted seals 250 may be coupled to the plurality of shoe plates 230 positioned against the inner diameter 152 of the storage tank 150. In particular, each liquid-mounted seal 250 may be coupled to the inner diameter of a shoe plate 230. In one implementation, each liquid-mounted seal 250 may be coupled to the shoe plate 230 such that the liquid-mounted seal 250 may be disposed below the adjustable arm assembly 220. For example, a liquid-mounted seal 250 may be coupled to a shoe plate 230 such that the liquid-mounted seal 250 is positioned below a lower flange 222 of the shoe plate 230. In another implementation, each liquid-mounted seal 250 may be disposed above the adjustable arm assembly 220. The liquid-mounted seal 250 may be coupled to the plurality of shoe plates 230 using plates, bolts, flanges, or any other fastening means known to those skilled in the art.
The one or more liquid-mounted seals 250 may collectively span the entire rim space 120 around the floating roof 150. Each liquid-mounted seal 250 may be disposed and compressed between the floating roof 100 and a shoe plate 230, such that the compressed liquid-mounted seal 250 may be in tension, thereby placing the liquid-mounted seal 250 in a stable position.
Each liquid-mounted seal 250 may include a cover, such as one made of fabric, that may be coupled to the inner diameter of a shoe plate 230. In one implementation, the cover may be composed of urethane. Within its cover, each liquid-mounted seal 250 may contain core, such as a foam core, a binding comb (as discussed below), or any other resiliently flexible material known to those skilled in the art. The cover may be sealed to substantially prevent the liquid product from entering the liquid-mounted seal 250 via the cover.
The one or more liquid-mounted seals 250 may accommodate horizontal movement of the floating roof 100. For example, each liquid-mounted seal 250 may be configured to compress or decompress against the shoe plate 230 as the floating roof 100 moves horizontally within the storage tank 150. The liquid-mounted seals 250 may also be positioned directly on the liquid product in the rim space 120, thereby minimizing the escape of evaporative emissions from the rim space 120. In particular, each liquid-mounted seal 250 may seal the rim space 120 such that there is substantially little gap between the floating roof 100 and the shoe plate 230. Further, the liquid-mounted seals 250 may be configured to move with the shoe plates 230 and the floating roof 100 in a vertical direction as the floating roof 100 rises and falls with changing amounts of the liquid product in the storage tank 150.
By positioning each liquid-mounted seal 250 between the floating roof 100 and a shoe plate 230 as described above, the shoe plate 230 may shield the cover of the liquid-mounted seal 250 from being damaged against the inner diameter 152 of the storage tank 150. In particular, the shoe plate 230 may protect the liquid-mounted seal 250 as the floating roof 100 traverses up and down inside the tank 150, thereby preventing the liquid product from entering the liquid-mounted seal 250 via a damaged cover. In scenarios where the liquid product is able to enter a damaged liquid-mounted seal 250, numerous hazards could develop, including the risk of fire, general contamination, and/or the like.
In a further implementation, the seal assembly 200 may also include a secondary seal 300, where the secondary seal 300 may include a secondary vapor barrier (not pictured) coupled to a wiper-type seal 310 positioned above the shoe seal 210. The secondary vapor barrier may be similar to the vapor barrier 240 described above. In one implementation, the wiper-type seal 310 may extend from a top part of the floating roof 100 or the base member 212, and may also extend towards the inner diameter 152 of the storage tank 150. In such an implementation, the wiper-type seal 310 may extend towards the inner diameter 152 at an angle. The wiper-type seal 310 may be composed of stainless steel or other material known to those skilled in the art, and there may be a little gap between the seal 310 and the inner diameter 152. Further, the secondary vapor barrier may be coupled to either a top portion or a bottom portion of the wiper-type seal 310, and may form a seal within the rim space 120. In particular, the secondary vapor barrier may extend along the wiper-type seal 310 from the inner diameter 152 and the floating roof 100.
The secondary seal 300 may also be configured to move in a horizontal direction or a vertical direction in conjunction with the floating roof 100. In an implementation using a plurality of seal assemblies 200, a plurality of the secondary seals 300 may be disposed along the floating roof 100. The plurality of secondary seals 300 may form a ring of wiper-type seals 310 around the rim space 120. In such an implementation, along with the shoe seal 210 and the liquid-mounted seal 250, the secondary seal 300 may provide added protection between the floating roof 100 and the inner diameter 152, thereby further minimizing an escape of evaporative emissions from the rim space 120. The secondary seals 300 may also help to prevent dropped items from falling into the liquid product. In one implementation, the secondary seals 300 may be optional.
As mentioned above, one or more binding combs may be placed inside the cover of a liquid-mounted seal 250.
In particular, the binding comb 400 may be composed of a base portion 410 having a series of picks 420, where the binding comb 400 has been rolled into a substantially cylindrical shape.
When the comb 400 is rolled into the substantially cylindrical shape, each pick may be rolled into a substantially circular shape, as shown in
In one implementation, the substantially cylindrical binding comb 400 may be placed inside covers of the liquid-mounted seals 250 for use instead of a foam core. In another implementation, the liquid-mounted seals 250 containing the binding combs 400 may be used to seal the rim space 120 without the additional use of the shoe seal 230 and/or the secondary seal 300. In such an implementation, the cover of liquid-mounted seal 250 may be coupled directly to an outer diameter of the floating roof 100, and the liquid-mounted seal 250 may be positioned directly against the inner diameter 152 of the storage tank 150. Such a liquid-mounted seal 250 may be configured to span the rim space 120 and to accommodate horizontal movement of the floating roof 100. For example, such a liquid-mounted seal 250 with the binding comb 400 may be configured to compress or decompress against the inner diameter 152 as the floating roof 100 moves horizontally within the storage tank 150. Such a liquid-mounted seal 250 may also be positioned directly on the liquid product in the rim space 120, thereby minimizing the escape of evaporative emissions from the rim space 120.
If the cover of such a liquid-mounted seal 250 were to become damaged against the inner diameter 152, the liquid product may enter the liquid-mounted seal 250. However, such a scenario may present fewer dangers than if the liquid product were to enter a liquid-mounted seal 250 having a foam core. For example, the risk of fire or contamination with a liquid-mounted seal 250 using a binding comb 400 may be minimized when compared to seals 250 which use a foam core.
In sum, the seal assembly 200 described with respect to
The discussion of the present disclosure is directed to certain specific implementations. It should be understood that the discussion of the present disclosure is provided for the purpose of enabling a person with ordinary skill in the art to make and use any subject matter defined herein by the subject matter of the claims.
It should be intended that the subject matter of the claims not be limited to the implementations and illustrations provided herein, but include modified forms of those implementations including portions of the implementations and combinations of elements of different implementations within the scope of the claims. It should be appreciated that in the development of any such implementation, as in any engineering or design project, numerous implementation-specific decisions should be made to achieve a developers' specific goals, such as compliance with system-related and business related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort maybe complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having benefit of this disclosure. Nothing in this application should be considered critical or essential to the claimed subject matter unless explicitly indicated as being “critical” or “essential.”
Reference has been made in detail to various implementations, examples of which are illustrated in the accompanying drawings and figures. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.
It should also be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first object or step could be termed a second object or step, and, similarly, a second object or step could be termed a first object or step, without departing from the scope of the invention. The first object or step, and the second object or step, are both objects or steps, respectively, but they are not to be considered the same object or step.
The terminology used in the description of the present disclosure herein is for the purpose of describing particular implementations and is not intended to limit the present disclosure. As used in the description of the present disclosure and appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify a presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
As used herein, the term “if” may be construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” may be construed to mean “upon determining” or “in response to determining” or “upon detecting [the stated condition or event]” or “in response to detecting [the stated condition or event],” depending on the context. As used herein, the terms “up” and “down”; “upper” and “lower”; “upwardly” and “downwardly”; “below” and “above”; and other similar terms indicating relative positions above or below a given point or element may be used in connection with some implementations of various technologies described herein.
While the foregoing is directed to implementations of various techniques described herein, other and further implementations may be devised without departing from the basic scope thereof, which may be determined by the claims that follow.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/032,416, filed Aug. 1, 2014, titled FLOATING ROOF SEAL, and the benefit of U.S. Provisional Patent Application Ser. No. 62/056,136, filed Sep. 26, 2014, titled FLOATING ROOF SEAL. The disclosures of both above-listed provisional patent applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62056136 | Sep 2014 | US | |
| 62032416 | Aug 2014 | US |
