Liquefied Gas Tank Bottom Wall Insulation
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Solution Overview
Problem
Gravity platform tanks lack sufficient thermal insulation and mechanical strength for efficiently storing and handling liquefied gases, particularly LNG, due to inadequate insulation between the tank walls and concrete base structures, and insufficient resistance to operational and accidental loads during loading and unloading.
Innovation Solution
A tank design featuring a bottom wall with a thermally insulating barrier composed of self-supporting polymer foam panels, where the density of the foam blocks varies to enhance both thermal insulation and mechanical strength, particularly around a drain area for improved pump efficiency and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If uniform density polymer foam panels are used throughout the tank bottom wall, then manufacturing simplicity is maintained, but thermal insulation effectiveness and mechanical strength at the drain area are insufficient
Solution Approach 1:
The patent applies local quality by varying the density of polymer foam blocks in different regions of the tank bottom wall. Specifically, the drain area uses higher density foam blocks to provide enhanced mechanical strength and thermal insulation where the pump suction creates concentrated loads, while other areas use lower density foam to minimize weight and manufacturing complexity. This regional differentiation resolves the contradiction by providing strength exactly where needed without complicating the entire structure.
Solution Approach 2:
The patent implements parameter changes by modifying the density parameter of the polymer foam material based on location. The foam blocks at the drain area have a higher density (e.g., 40-80 kg/m³) compared to blocks in other areas (e.g., 20-40 kg/m³). This parameter variation allows the structure to achieve higher mechanical strength and thermal insulation performance at the critical drain location while maintaining overall manufacturing feasibility through standardized block production.
2Ease of manufacture
If the tank bottom wall structure is simplified, then manufacturing costs are reduced, but thermal insulation performance between the tank and concrete base structure deteriorates
Solution Approach 1:
The patent uses composite materials by combining polymer foam blocks with a plate structure (such as steel or concrete plates) to create a composite panel system. The polymer foam provides thermal insulation, while the plate provides structural strength and a stable mounting surface for the drain. This composite approach achieves good thermal insulation performance without requiring complex multi-layer structures, thus maintaining ease of manufacture and cost-effectiveness.
Solution Approach 2:
The patent applies segmentation by dividing the bottom wall into modular panels, each consisting of polymer foam blocks supported by a plate. These standardized panels can be manufactured separately and assembled on-site, reducing manufacturing complexity and cost. The segmented design also allows for easy replacement and maintenance, while the cumulative effect of multiple panels provides the required thermal insulation performance across the entire tank bottom.
3Reliability
If higher density polymer foam is used at the drain area, then mechanical strength and thermal insulation are improved, but material cost increases
Solution Approach 1:
The patent applies local quality by using higher density polymer foam blocks (providing greater mechanical strength and thermal insulation) only at the drain area where the pump suction creates concentrated operational loads. Other areas of the tank bottom wall use lower density foam that is sufficient for their lighter loading conditions. This localized approach achieves the required reliability at the critical drain location while minimizing overall material cost by avoiding unnecessary high-density foam throughout the entire structure.
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
The design improves thermal insulation and mechanical strength, optimizing the storage and handling of liquefied gases while minimizing manufacturing costs and complexity, ensuring effective liquefied gas pumping and reduced residual gas levels.
Implementation Method 1
a thermally insulating barrier (61) composed of self-supporting panels (63) each comprising a block of polymer foam (65)
Implementation Method 2
The blocks of polymer foam (65) of the second portion (31) have a density greater than a density of the blocks of polymer foam (65) of the first portion (29)
Data Source
AI summary
A tank for transporting and/or storing a liquefied gas includes: a plurality of walls, each including, in a direction of the thickness of the wall, a thermally insulating barrier and a leak-tight membrane that rests against the thermally insulating barrier and is intended to be in contact with the liquefied gas inside the tank, the thermally insulating barrier including a plurality of self-supporting heat-insulating panels which each includes a block of polymer foam and a plate, a bottom wall of the plurality of walls includes a first portion at least partially surrounding a second portion of the bottom wall, the second portion including drain. The blocks of polymer foam of the second portion have a density greater than a density of the polymer foam blocks of the first portion.