Air separation apparatus, adsorber, and method
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Solution Overview
Problem
Air separation unit (ASU) systems face operational challenges due to nitrous oxide (N2O) and carbon dioxide (CO2) breakthroughs, leading to equipment failures and increased capital costs, as conventional methods require redundant chillers or larger pre-purification units to maintain safety and efficiency.
Innovation Solution
The system allows for temporary elevated levels of N2O to pass through the pre-purification unit (PPU) while maintaining CO2 control, enabling the ASU to operate at full capacity during chiller failures, reducing capital costs and operational inefficiencies by using a smaller PPU and less molecular sieve adsorbent material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pre-purification units are designed to completely remove N2O and CO2, then safety and operational reliability are improved, but capital costs increase due to requiring redundant chillers or larger PPU equipment
Solution Approach 1:
The patent changes the operational parameters by establishing different threshold levels for N2O (first threshold) compared to CO2 (second threshold). The system allows N2O to pass through at elevated levels between these thresholds while maintaining strict CO2 control, thereby reducing the need for oversized equipment or redundant chillers while preserving safety
Solution Approach 2:
The system dynamically adjusts its response based on which impurity is detected and at what concentration. Rather than using a static, overly conservative design, the control system responds differently to N2O versus CO2 breakthrough, allowing optimized equipment sizing that reflects actual operational risks
2Productivity
If the PPU is designed larger to handle chiller failures, then operational continuity is improved, but capital costs and operational costs increase
Solution Approach 1:
The system prepares for chiller failures by pre-establishing elevated N2O thresholds and having the control logic ready to permit higher N2O levels during such events. This preliminary configuration allows the system to maintain productivity during failures without requiring physically larger equipment
3Object-affected harmful factors
If N2O is strictly controlled to below very low thresholds, then downstream processing safety is improved, but operational flexibility during chiller failures deteriorates
Solution Approach 1:
The patent applies different quality standards to different impurities: a very strict threshold for CO2 (second threshold) and a more lenient threshold for N2O (first threshold). This local differentiation of control criteria allows the system to maintain downstream safety while gaining operational flexibility during chiller failures
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 allows for reliable and uninterrupted ASU operation during chiller trips, reducing capital and operational costs, and maintaining safety by adjusting the defrost interval to mitigate N2O accumulation, thereby enhancing profitability and operational flexibility.
Implementation Method 1
a bed of adsorbent material positioned in the vessel; the bed of adsorbent material configured to remove water and carbon dioxide (CO2) from a compressed air flow fed to the PPU and is also configured to remove nitrous oxide (N2O)
Data Source
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AI summary
A method of purifying air via a pre-purification unit (PPU) (107) of an air separation unit (ASU) system (1) having a pre-PPU chiller (104) that is upstream of the PPU (107) to cool compressed air before the compressed air is fed to the PPU (107) can include passing air through an adsorber (200) of the PPU (107) to pass the air through a bed (205,207) of adsorbent material within a vessel (203) of the adsorber (200). In response to the pre-PPU chiller (104) being determined to have an issue resulting in the pre-PPU chiller (104) being tripped or requiring the pre-PPU chiller (104) to be taken off-line, continuing to operate the ASU system (1) at a full capacity even though nitrous oxide (N2O) within the air output from the PPU (107) exceeds a first pre-selected threshold and is below a second pre-selected threshold associated with carbon dioxide (CO2) breakthrough. An ASU (1) and a PPU (107) can be designed to implement an embodiment of the method.