Combined Permeation of Pressurised CO2 with Impurities through Thermoplastics
Status: Proposal
Date Announced: July, 2024
Project reference: PROP311581
Summary
Overview
In applications for carbon capture and storage or enhanced oil recovery that include steel pipe remediation or liners for thermoplastic composite pipe, there is a need to assess the barrier performance of thermoplastic polymers. Specifically, this is to establish their effectiveness as barrier layers to impurities in carbon dioxide (CO2) feedstock such as water vapour, ammonia, nitrous oxide, hydrogen and hydrogen sulfide. Generally, the liner reduces the rate of arrival of corrosive species at the load bearing steel support wires or base pipe.
The CO2 fluid compositions may vary between locations and, potentially, there will be an enormous cost and environmental impact in needing to expose thermoplastic systems to each fluid composition on a case by case basis using autoclave-based ageing studies.
This study aims to establish whether some impurities are selectively blocked by the internal structure of the thermoplastic resin, allowing them to be excluded from screening studies for ageing in the future. This work will provide guidance as to which impurities within CO2 compositions are most relevant when assessing the barrier properties and ageing of thermoplastics.
The chosen thermoplastics may be from the polyethylene, polyphenylene sulfide or polyvinylidiene families, and will be determined by the Sponsors. TWI Ltd will work with the Joint Industry Project (JIP) sponsors and third party suppliers to acquire the pre-prepared specimens as appropriate for the JIP.
Project Concept
Establish selectivity for impurities in the presence of pressurised CO2
The project will use the established TWI permeation facility, supported by gas chromatographs, to measure over several months the rate of transport through thermoplastics of CO2 with water vapour and trace amounts of one of hydrogen sulphide, ammonia, nitrous oxide or hydrogen. It is expected that the concentrations of the impurities will be of the order of 500ppm. In any one permeation test, the pressures and temperatures of the CO2 feed can start in the gaseous phase and be pressurised to liquid at 250barg with the temperature altered above 31°C to create a supercritical fluid.
Where transport is detected, then the flux and permeability coefficients will be calculated for each species at each pressure and temperature step. This may allow the activation energy for permeation to be determined. Assuming that initial breakthrough is captured, then diffusion coefficients will be calculated at various temperatures with the potential to estimate the solubility and enthalpy of adsorption of each component.
Using this data, it is hoped that the expected transport levels at other pressure and temperature conditions can be estimated. The analysis of the thermoplastic will be for swelling, alteration in crystallinity, glass transition temperature, storage and loss modulus.
Objectives
- To establish the barrier performance of thermoplastic materials to CO2 with associated impurities.
- To establish if any transport of these impurity species causes ageing in the thermoplastic matrix.
Benefits
This work will provide guidance as to which generic CO2 composition with impurities are relevant to assess the barrier properties and ageing of thermoplastics.
If you are interested in finding out more, see the PDF download. If you would like to join this JIP, please contact us.