Air Compression Staging for Mid-Pressure TSA Purification
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Solution Overview
Problem
Air separation plants face high fabrication and operational costs due to the need for high-pressure adsorbent beds in temperature swing adsorption units, which increase power consumption and material costs during depressurization and vessel fabrication.
Innovation Solution
A multistage air compression system with a temperature swing adsorption unit situated in an intermediate location, operating at pressures between 400 psia and 600 psia, using molecular sieve adsorbent beds to reduce water vapor and carbon dioxide levels, with interstage cooling to minimize adsorbent requirements and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature swing adsorption unit operates at higher pressures (above conventional levels), then the adsorption effectiveness improves and water vapor removal is enhanced, but the power consumption increases and fabrication costs rise
Solution Approach 1:
The patent applies parameter changes by operating the temperature swing adsorption unit at an optimized pressure range of 400-600 psia, which is higher than conventional pressures but controlled within a specific range to balance adsorption effectiveness with power consumption and fabrication costs. This parameter optimization resolves the contradiction by finding the sweet spot where adsorption performance is sufficient without incurring excessive energy and cost penalties.
2Reliability
If the temperature swing adsorption unit operates at higher pressures, then the adsorption effectiveness improves, but the fabrication costs increase due to thicker vessel walls
Solution Approach 1:
The patent resolves this contradiction by specifying an optimized pressure range of 400-600 psia that provides sufficient adsorption effectiveness while controlling fabrication costs. Additionally, the patent applies principle of local quality by using different adsorbent materials (alumina and molecular sieve) in different layers of the bed, which allows effective adsorption at moderate pressures without requiring excessively thick vessel walls.
3Reliability
If more adsorbent is used to remove water vapor and carbon dioxide, then the purification effectiveness improves, but the device complexity and cost increase
Solution Approach 1:
The patent applies local quality by using different adsorbent materials in different regions of the adsorbent bed. Specifically, alumina is used in the lower layer to adsorb water vapor, while molecular sieve is used in the upper layer to adsorb carbon dioxide. This layered approach with different adsorbent properties optimizes purification effectiveness for different contaminants while avoiding the need for excessive amounts of a single adsorbent material, thus reducing device complexity and cost.
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 configuration balances costs by reducing power consumption and adsorbent needs while maintaining effective impurity removal, with potential for smaller vessel diameters to minimize fabrication costs, achieving a more cost-effective air pre-purification process.
Implementation Method 1
A temperature swing adsorption unit is provided to adsorb water vapor and carbon dioxide. The temperature swing adsorption unit includes adsorption beds having at least one adsorbent formed from molecular sieve.
Implementation Method 2
Interstage cooling between the compressors to cool the air and remove water vapor.
Data Source
AI summary
An air compression system and method for an air separation plant in which air is compressed in a series of compression stages and a temperature swing adsorption unit adsorbs water vapor and carbon dioxide. The temperature swing adsorption unit is situated at a location of the compression stages such that air pressure upon entry into the adsorbent beds is between about 400 psia and about 600 psia. Each of the adsorbent beds of the unit have a minimum transverse cross-sectional flow area that will set the air velocity of the air to a level below that at which adsorbent bed fluidization would occur. Such operation allows fabrication costs of the adsorbent beds to be reduced because less adsorbent and smaller adsorbent beds are required while power consumption will be at a minimum.