Core-in-shell composite adsorbent for use in PSA prepurifiers
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Solution Overview
Problem
Conventional adsorbents in PSA processes for air prepurification in cryogenic air separation units suffer from incomplete regeneration, leading to reduced dynamic capacity and increased operational costs due to frequent bed blowdown and repressurization, which results in air loss and higher power requirements.
Innovation Solution
Development of attrition-resistant core-in-shell composite adsorbents with a zeolite-containing shell and an inert dense core, specifically designed to enhance mass transfer rates and physical strength, allowing for extended cycle times and improved volumetric performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional adsorbents are used in PSA processes, then the adsorption capacity is maintained, but the dynamic capacity is reduced due to incomplete regeneration
Solution Approach 1:
The adsorbent particle is segmented into a core-in-shell structure with an inert dense core and an adsorbent shell. This segmentation allows the shell to be optimized for adsorption while the core provides mechanical strength, resolving the contradiction between maintaining adsorption capacity and improving dynamic capacity through better regeneration.
Solution Approach 2:
The invention uses composite materials combining an inert dense core material with an adsorbent shell material. This composite structure enables the particle to simultaneously achieve high adsorption capacity in the shell and improved mechanical properties for complete regeneration, thereby improving dynamic capacity while maintaining adsorption capacity.
2Loss of substance
If PSA process cycle time is extended, then air loss during blowdown is reduced, but adsorbent regeneration becomes incomplete
Solution Approach 1:
The core-in-shell structure segments the particle functions, allowing the shell to perform adsorption while the core provides mechanical strength. This enables extended cycle times without compromising regeneration completeness, as the strengthened particle can withstand the mechanical stresses of longer cycles while maintaining full regeneration capability.
Solution Approach 2:
The invention enables dynamic operation at extended cycle times by improving adsorbent durability. The enhanced mechanical strength allows the adsorbent to maintain performance over longer operational cycles, reducing air loss during blowdown while ensuring complete regeneration is still achieved at the extended cycle endpoint.
3Speed
If adsorbent particle size is reduced to increase mass transfer rate, then mass transfer improves, but attrition resistance decreases
Solution Approach 1:
The particle is segmented into a small-sized adsorbent shell for high mass transfer rate and a mechanically strong core for attrition resistance. This segmentation allows the shell to be thin and highly porous for rapid mass transfer while the core provides the mechanical strength needed to resist attrition, resolving the contradiction between mass transfer rate and attrition resistance.
Solution Approach 2:
The composite core-in-shell structure combines materials with complementary properties: the adsorbent shell material provides high surface area and porosity for rapid mass transfer, while the inert dense core material provides mechanical strength and attrition resistance. This composite approach simultaneously achieves high mass transfer rate and maintained attrition resistance.
4Productivity
If bed blowdown frequency is increased to maintain adsorption capacity, then adsorption performance is maintained, but operational cost increases
Solution Approach 1:
The invention enables extended operational cycles by improving adsorbent durability through the core-in-shell structure. The enhanced mechanical strength allows the adsorbent to maintain high adsorption performance over longer periods without requiring frequent blowdown, thereby reducing the frequency of energy-intensive regeneration cycles and lowering operational costs.
Solution Approach 2:
The strengthened adsorbent allows for longer continuous operation between blowdown events, maintaining high adsorption performance throughout extended cycles. This continuity of useful action reduces the number of times the system must interrupt operation for regeneration, thereby reducing energy losses and operational costs associated with frequent bed blowdown.
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 attrition-resistant core-in-shell composite adsorbents exhibit significantly improved working capacity and volumetric performance, reducing air loss and operational costs by maintaining high efficiency in CO2 removal and other impurity separation, outperforming conventional adsorbents by 30-70% in PSA systems.
Implementation Method 1
a zeolite-containing CO2 removal adsorbent shell... for removing at least CO2 from a feed gas stream in a cyclic pressure swing adsorption (PSA) process
Implementation Method 2
specifically designed to enhance mass transfer rates and physical strength
Data Source
AI summary
The present invention relates generally to an attrition resistant core-in-shell composite adsorbent comprising at least a zeolite-containing CO2 removal adsorbent and a binder on an inert dense core. The attrition resistant core-in-shell composite adsorbent has an attrition loss of less than about 2 wt %. The core-in-shell composite adsorbent is preferably used in a multi-layered adsorption system in a cyclic adsorption process, preferably used in a PSA prepurification process prior to cryogenic air separation.