Polymeric Inner Liner Welding for Hydrogen Storage Tanks
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Solution Overview
Problem
Conventional storage tanks designed for compressed methane do not meet the expected more restrictive permeation requirements for compressed hydrogen, and existing methods for manufacturing multilayer polymeric inner liners are complex and prone to connection issues affecting mechanical performance and permeability.
Innovation Solution
A method involving a cylindrical body and dome-shaped end cap with inward-bended peripheral connection tabs for welding, utilizing a structural layer and barrier layer configuration, allowing for a strong and impermeable connection without complex injection molding, using conventional blow molding techniques and over molding of accessories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tanks are used for compressed hydrogen storage, then the tank structure is simple, but the permeation requirements are not met
Solution Approach 1:
The patent applies composite materials by creating a multilayer polymeric inner liner combining a structural layer (providing mechanical strength) and a barrier layer (providing permeation resistance). This composite structure resolves the contradiction by achieving both the required permeation resistance for hydrogen storage and maintaining a relatively simple overall tank design, as the multilayer liner can be manufactured using conventional blow molding techniques.
2Reliability
If multilayer liner is used to improve permeability, then the permeation resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the liner into distinct structural and barrier layers, each optimized for its specific function. The structural layer provides mechanical strength while the barrier layer provides permeation resistance. This segmentation allows each layer to be manufactured separately using conventional blow molding techniques and then joined together, simplifying the overall manufacturing process compared to attempting to create a monolithic multilayer structure through complex injection molding.
Solution Approach 2:
The patent applies preliminary action by pre-forming the structural and barrier layers separately using conventional blow molding techniques before joining them together. This approach allows each layer to be optimized and manufactured independently, reducing the complexity of the final assembly process and enabling the use of existing manufacturing infrastructure.
3Ease of manufacture
If end caps are welded to cylindrical body, then the manufacturing simplicity is improved, but the connection reliability deteriorates
Solution Approach 1:
The patent applies merging by integrating the connection tabs directly into the molded structures of the end caps and cylindrical body. The connection tabs are formed as integral parts of the components during the blow molding process, eliminating the need for separate fastening hardware. This merging of the connection feature into the base structure maintains manufacturing simplicity while significantly improving connection reliability through direct welding of the integrated tabs.
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 method produces an inner liner with excellent permeation qualities, suitable for hydrogen storage, reducing emissions and enabling cost-effective production with improved mechanical properties, facilitating the storage of hydrogen gas while minimizing the risk of permeability and mechanical failure.
Implementation Method 1
welding both connection tabs together
Data Source
Figure 1
AI summary
A method for manufacturing a polymeric inner liner for a storage tank, in particular for a hydrogen storage tank, wherein the method comprises the steps of: providing a cylindrical body made from polymer material and comprising a structural layer and a barrier layer, said cylindrical body having a first open end and a first peripheral connection tab at said open end; providing a dome-shaped end cap made from polymer material, the end cap having a base with a cross-section essentially corresponding to a cross-section of the first open end of the cylindrical body and having a second peripheral connection tab at a peripheral end portion of said end cap; placing the end cap with its base onto the first open end of the cylindrical body and with said first and second peripheral tabs in contact with each other; and welding both connection tabs together. Storage tank made using such a liner and use of such a tank for storing hydrogen.