Seal Extension for Double Seal Floating Roof Tanks

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Solution Overview

Problem

Conventional double seal arrangements in large cylindrical hydrocarbon storage tanks limit the maximum capacity by reserving space for vapor containment, resulting in a significant loss of storage volume, which is economically undesirable for facilities that need to maximize storage without expanding infrastructure.

Innovation Solution

A lightweight seal extension is added to the top peripheral edge of the tank, allowing the second seal to rise above the tank's structural top while maintaining a seal, thereby increasing the liquid storage capacity without compromising vapor containment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a double seal arrangement is used to contain vapor space, then vapor containment is improved, but storage capacity is reduced

Engineering Contradiction:

Improvevapor containmentVSAvoidstorage capacity

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The seal extension protrudes upward from the tank wall in the vertical dimension, allowing the second seal to operate at a higher elevation than the tank wall top. This dimensional extension enables the seal system to maintain vapor containment while the liquid level can rise to the actual tank top, recovering lost storage capacity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The seal extension acts as an intermediary structure between the tank wall and the floating roof seal system. It provides a dedicated surface for the second seal to engage, allowing the seal to rise above the tank wall while maintaining effective vapor containment through the seal's contact with the extension surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the second seal is positioned above the primary seal by 18-36 inches, then vapor containment is improved, but storage capacity is reduced

Engineering Contradiction:

Improvevapor containmentVSAvoidstorage volume

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The seal extension extends the vertical dimension of the seal system above the tank wall, allowing the second seal to be positioned higher than previously possible. This enables the liquid level to approach the tank top while maintaining the necessary vertical separation between seals for vapor containment.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Strength

If the tank is filled to the top of the wall, then structural integrity is maintained, but storage capacity is maximized

Engineering Contradiction:

Improvestructural integrityVSAvoidstorage capacity

Core Design Contradiction:

StrengthVSVolume of stationary object

Solution Approach 1:

The seal system is segmented into two separate seals positioned at different heights, with the second seal engaging with the seal extension above the tank wall. This segmentation allows the liquid to be filled to the tank top while the seal extension provides the necessary vapor containment function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The seal extension serves as an intermediary structure that enables the second seal to function at an elevated position above the tank wall. This intermediary allows the tank to be filled to its full structural capacity while maintaining vapor containment through the seal's engagement with the extension.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution effectively recovers additional storage capacity by enabling the liquid level to approach the tank's true top, adding substantial gallons of storage without requiring new tank installations, thus offering a cost-effective means to enhance revenue for storage facilities.

Implementation Method 1

a floating roof that floats on the liquid surface using flotation pontoons or other flotation arrangement

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 2

two or more seals are positioned around the periphery of the floating roof to be in contact with the inside wall of the tank to seal the small vapor space from the outside atmosphere and prevent hydrocarbon releases

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS11186432B2External floating roof tank shell extension

Publication Date: 2021.11.30 PHILLIPS 66 CO

AI summary

The invention relates to an inexpensive technique and procedure to add storage capacity to existing hydrocarbon storage tanks that have a double seal floating roof. The additional storage capacity is obtained by installing an extension that is strong enough to provide the upper seal of the double seal arrangement to maintain a sealed vapor space that allows the roof to move higher within the existing peripheral wall of the storage tank.