Temperature Swing Adsorption for Compact Cryogenic Air Purification
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Solution Overview
Problem
Conventional cryogenic air separation systems face challenges in downsizing due to large adsorption column diameters, which lead to issues with gas dispersion and increased installation areas, while existing methods for removing nitrogen oxides and hydrocarbons are inefficient and energy-intensive.
Innovation Solution
A purification method using a temperature swing adsorption method where the entire region of a carbon dioxide adsorbent layer is utilized as a mass transfer zone, allowing for simultaneous removal of carbon dioxide, nitrogen oxide, and hydrocarbons, with a carbon dioxide adsorbent packed to 100% to 140% of the calculated amount, and a gas velocity of 0.25 to 0.4 m/s to optimize adsorbent usage and column size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cross-sectional area of an adsorption column is increased to handle higher feed air flow rates, then the productivity increases, but the installation area and gas dispersion problems worsen
Solution Approach 1:
The patent changes the operating parameters by optimizing the air velocity range (0.15-0.35 m/s) and adsorbent layer height-to-diameter ratio (0.5-2.0) to enable efficient adsorption in a more compact column configuration, allowing higher productivity without proportionally increasing installation area
Solution Approach 2:
The patent shifts the design focus from increasing column diameter (horizontal dimension) to optimizing column height and adsorbent layer thickness (vertical dimension), thereby achieving higher feed air flow rates without significantly increasing the footprint installation area
2Reliability
If the amount of adsorbent is increased to improve impurity removal capacity, then the purification effectiveness improves, but the adsorption column height and installation area increase
Solution Approach 1:
The patent optimizes the adsorbent layer height within a specific range (0.5-2.0 times the column diameter) and controls air velocity (0.15-0.35 m/s) to maximize adsorption efficiency per unit volume, achieving high impurity removal capacity without excessive column height
Solution Approach 2:
The patent uses highly effective adsorbent materials with superior impurity capture properties, allowing a smaller amount of adsorbent to achieve the same purification effectiveness that would require larger quantities of conventional adsorbents
3Productivity
If the air velocity is increased to process more feed air, then the productivity increases, but the adsorbent may be blown up and fluidized
Solution Approach 1:
The patent identifies and maintains air velocity within the optimal range of 0.15-0.35 m/s, which is high enough to achieve good productivity but low enough to prevent adsorbent fluidization and layer instability, thereby balancing productivity and reliability
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 approach results in a more compact and energy-efficient purification apparatus with reduced adsorbent requirements, achieving substantial removal of nitrogen oxides and hydrocarbons alongside carbon dioxide, while minimizing pressure loss and installation area.
Implementation Method 1
purifying the feed air for the cryogenic air separation by using a temperature swing adsorption method
Implementation Method 2
a temperature swing adsorption method where the entire region of a carbon dioxide adsorbent layer is used as a mass transfer zone of a carbon dioxide
Data Source
AI summary
A purification method for feed air in cryogenic air separation of the present invention includes purifying the feed air for the cryogenic air separation by using a temperature swing adsorption method, wherein the whole region of a carbon dioxide adsorbent layer packed in an adsorption column is used as a mass transfer zone of a carbon dioxide. Also, a purification apparatus for feed air in cryogenic air separation of the present invention includes at least two adsorption columns; and a moisture adsorbent and a carbon dioxide adsorbent being laminated and packed in the adsorption columns, wherein the packed amount of the carbon dioxide adsorbent is the same as the amount of the carbon dioxide adsorbent in the region of the carbon dioxide adsorbent which a mass transfer zone of a carbon dioxide occupies at the end of an adsorption step, and a temperature swing adsorption method is used.