Layered Adsorbent Bed for Oxygen PSA Impurity Management
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Solution Overview
Problem
Small, rapid-cycle pressure swing adsorption (PSA) systems for oxygen concentrators face significant performance decline due to feed gas impurities like water and carbon dioxide, leading to progressive deactivation of adsorbent materials and requiring frequent replacement or oversized adsorbent beds, which increase cost and weight.
Innovation Solution
A pressure swing adsorption process with a layered adsorbent vessel design, where the first layer is selective for water adsorption and the second layer is selective for nitrogen, using activated alumina and lithium-exchanged zeolites, with optimized superficial contact time, bed geometry, and heat transfer to maintain oxygen purity and extend adsorbent life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If small adsorbent beds are used in rapid-cycle PSA systems, then the system becomes more portable and lighter, but the adsorbent experiences progressive deactivation due to feed gas impurities
Solution Approach 1:
The adsorbent bed is divided into multiple functional layers: a first layer selective for water adsorption and a second layer selective for nitrogen adsorption. This segmentation allows each layer to perform its specific function optimally, preventing impurity accumulation in the nitrogen-selective layer and maintaining stable performance over time.
Solution Approach 2:
The first layer of water-selective adsorbent performs preliminary removal of water impurities from the feed gas before the gas enters the second layer. This preliminary action protects the nitrogen-selective adsorbent from water contamination and maintains its activity over extended periods.
2Duration of action of stationary object
If oversized adsorbent beds are used to account for progressive deactivation, then adsorbent replacement frequency is reduced, but the cost and weight of the system increase
Solution Approach 1:
By segmenting the adsorbent bed into functional layers with specific selectivities, the system achieves stable performance without requiring oversized beds. The first layer handles water removal while the second layer handles nitrogen removal, allowing optimized bed dimensions that reduce weight while maintaining long service life.
3Reliability
If the first layer of adsorbent is made very deep to ensure complete water removal, then water adsorption effectiveness increases, but the superficial contact time decreases and performance stability is compromised
Solution Approach 1:
The patent optimizes the depth of the first layer to achieve the minimum required for effective water removal while maintaining adequate superficial contact time. By carefully selecting the depth parameter and using water-selective adsorbent material, the system achieves complete water removal without excessive contact time requirements.
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 process effectively removes water and nitrogen impurities, maintaining high oxygen recovery and extending the life of adsorbent materials, thereby reducing the need for frequent replacement and minimizing system weight and cost.
Implementation Method 1
adsorbing at least a portion of the water in the adsorbent material in the first layer
Implementation Method 2
adsorbing at least a portion of the nitrogen in the adsorbent material in the second layer
Data Source
AI summary
Pressure swing adsorption process for producing oxygen comprising (a) providing at least one adsorber vessel having a first layer of adsorbent adjacent the feed end of the vessel and a second layer of adsorbent adjacent the first layer, wherein the surface area to volume ratio of the first layer is in the range of about 0.75 to about 1.8 cm−1; (b) introducing a pressurized feed gas comprising at least oxygen, nitrogen, and water into the feed end, adsorbing at least a portion of the water in the adsorbent in the first layer, and adsorbing at least a portion of the nitrogen in the adsorbent in the second layer, wherein the superficial contact time of the pressurized feed gas in the first layer is between about 0.08 and about 0.50 sec; and (c) withdrawing a product gas enriched in oxygen from the product end of the adsorber vessel.