CO2 Gas Purification Using Water-Selective Adsorbent Beds
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Solution Overview
Problem
Current methods for purifying CO2 streams from oxycombustion, particularly those containing CO2, water, and impurities like NOx and SOx, are inadequate in ensuring complete elimination of contaminants, especially water, which can cause blocking issues during low-temperature treatment, transport, or storage.
Innovation Solution
A method involving successive steps including pretreatment, compression, and a purification step using adsorbents neutral to NOx and SOx, such as silica gel, porous glass, and specific zeolites, to preferentially eliminate water and other impurities, ensuring the CO2 stream is purified and suitable for storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional purification methods are used to treat CO2 streams containing water and impurities, then treatment capacity is maintained, but water elimination is incomplete causing blocking problems during low-temperature treatment and storage
Solution Approach 1:
The purification step is positioned before the low-temperature treatment step, performing water elimination in advance to prevent blocking problems during subsequent cooling, compression, and storage operations. This preliminary action ensures that water is removed while the gas is still in a state conducive to effective purification.
Solution Approach 2:
The patent employs porous adsorbent materials with specific pore structures and surface properties that enable preferential adsorption of water molecules from the CO2 stream. These materials provide high surface area and tailored pore sizes that enhance water capture efficiency while maintaining CO2 permeability.
2Reliability
If purification step is placed early in the process, then water elimination effectiveness is improved, but device volume and cost increase
Solution Approach 1:
The patent optimizes operating parameters including temperature, pressure, and gas flow rate to enhance water elimination efficiency within a compact purification unit. By adjusting these parameters, the system achieves high water removal effectiveness without requiring excessive purification media volume.
Solution Approach 2:
The purification system uses composite adsorbent materials that combine multiple functional properties in a single structure, maximizing water capture capacity per unit volume. This reduces the overall volume of the purification unit while maintaining or enhancing elimination effectiveness.
3Reliability
If adsorbents that strongly adsorb water are used, then water elimination is enhanced, but adsorbents become sensitive to NOx and SOx impurities
Solution Approach 1:
The patent employs a multi-stage purification approach where different adsorbent materials with specific local properties are used in sequence. The first stage uses adsorbents optimized for water capture, while subsequent stages use materials that protect against or remove NOx and SOx, preventing impurity damage to the primary water-removal adsorbents.
Solution Approach 2:
The system introduces protective intermediary layers or pre-treatment stages that shield the water-elimination adsorbents from harmful NOx and SOx impurities. These intermediaries either remove the harmful impurities first or provide a protective barrier that prevents impurity adsorption on the water-capture materials.
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 method effectively reduces the concentration of water and other impurities to non-blocking levels, enhancing the purity and safety of CO2 for storage, while minimizing the volume and cost of the purification unit by optimizing the placement of the purification step within the compression process.
Implementation Method 1
a purification step is carried out between steps a) and c) in which use is made of at least one bed of adsorbents that are neutral to NOx and/or SOx and have adsorption properties enabling water to be eliminated
Data Source
AI summary
A method for the purification of a feed gas stream containing CO2 and water and at least one impurity chosen from NOx and SOx, comprising the incorporation of a purification step for the preferential elimination of water is provided.