Composite Adsorbent for PSA Air Prepurification
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Solution Overview
Problem
Conventional pressure swing adsorption (PSA) processes for air prepurification in cryogenic air separation units suffer from incomplete regeneration of adsorbents, leading to reduced dynamic capacity and frequent bed blowdown, resulting in significant air loss and increased operational costs.
Innovation Solution
A composite adsorbent comprising zeolites and a metal oxide with a heat capacity of at least 20 cal/mol-°K is used in a multi-layered adsorption system, where the first layer removes water vapor and the second layer, containing zeolites and the metal oxide, effectively captures CO2 and other impurities, enhancing the working capacity and reducing the frequency of bed switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional PSA adsorbents are used, then the adsorption process can operate with simple equipment and low capital cost, but the adsorbents do not get completely regenerated leading to reduced dynamic capacity and frequent bed blowdown
Solution Approach 1:
The patent changes the thermal parameters of the adsorbent by incorporating metal oxides with high heat capacity (at least 20 cal/mol-°K) into the zeolite-alumina composite. This parameter change in the adsorbent's thermal properties enables better heat management during adsorption/desorption cycles, achieving more complete regeneration and extended cycle times without compromising dynamic capacity
Solution Approach 2:
The patent creates a composite adsorbent material combining zeolite, alumina, and metal oxide components. This composite structure integrates the high CO2 adsorption capacity of zeolite with the thermal management capabilities of metal oxides having high heat capacity, resulting in improved regeneration efficiency and extended operational cycle times
2Productivity
If bed blowdown frequency is increased to maintain adsorbent capacity, then dynamic capacity is maintained, but air loss and operational costs increase significantly
Solution Approach 1:
By modifying the thermal parameters of the adsorbent through metal oxide addition, the patent enables longer cycle times between blowdown events. The high heat capacity metal oxides absorb and release heat during cycling, maintaining adsorbent performance and allowing extended operation without regeneration, thereby reducing air loss during frequent bed switches
Solution Approach 2:
The patent extends the continuous operational period of the adsorbent bed by achieving more complete regeneration. This reduces the frequency of interrupting the useful adsorption action for bed blowdown and repressurization, maintaining continuous productive operation and minimizing air loss during transition phases
3Productivity
If TSA process is used instead of PSA, then adsorbent regeneration is more complete, but much higher purge flow requirements and complex thermal management are needed
Solution Approach 1:
The patent changes the thermal response parameters of the adsorbent by incorporating metal oxides with high heat capacity. This modification enables the PSA process to achieve regeneration completeness approaching TSA levels by better managing the thermal dynamics during pressure cycling, reducing the need for excessive purge flows
Solution Approach 2:
The metal oxide acts as a thermal intermediary within the adsorbent composite, absorbing and releasing heat during the PSA cycle. This internal thermal management mechanism mediates the thermal challenges of PSA regeneration, achieving near-TSA completeness without requiring the high purge flows typical of conventional PSA
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 composite adsorbent significantly improves the working capacity and operational efficiency of the PSA process by extending cycle times, reducing air loss, and lowering operational costs through enhanced thermal management and CO2 removal capabilities.
Implementation Method 1
a composite adsorbent comprising a CO2 adsorbent and a metal oxide
Implementation Method 2
10% or more of a metal oxide having a heat capacity of at least 20 cal/mol-° K
Data Source
AI summary
The present invention relates generally to a composite adsorbent comprising at least a zeolite-containing CO2 removal adsorbent and 10% or more of a metal oxide having a heat capacity of at least 20 cal/mol-° K (83.7 J/(mol·K). The composite is preferably used in a multi-layered adsorption system in a cyclic adsorption process. The adsorption system comprises two or more layers wherein the first layer is at least a water vapor removal adsorbent, such as activated alumina, and the second layer is the novel composite adsorbent. The adsorption system is preferably used in a PSA prepurification process prior to cryogenic air separation.