Purification of argon through liquid phase cryogenic adsorption
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Solution Overview
Problem
Current adsorption processes for purifying liquid argon from oxygen impurities are energy-intensive, require expensive vacuum regeneration, and use adsorbents that need reducing agents like hydrogen, making them costly and inefficient for large-scale operations, especially in air separation units (ASUs).
Innovation Solution
A Temperature Swing Adsorption (TSA) process using modified zeolite 4A adsorbents that regenerates by purging with warm nitrogen or argon streams above cryogenic temperatures, eliminating the need for vacuum pretreatment and reducing energy consumption, with a continuous cyclic process that maintains adsorbent effectiveness for extended on-line periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum regeneration is used to desorb oxygen from the adsorbent, then the adsorbent can be regenerated for reuse, but the energy consumption and equipment complexity increase significantly
Solution Approach 1:
The patent changes the regeneration parameter from vacuum pressure to temperature increase. Instead of using vacuum to desorb oxygen, the system uses thermal energy to heat the adsorbent bed, causing oxygen to desorb at elevated temperatures. This parameter change eliminates the need for vacuum equipment and significantly reduces energy consumption while maintaining effective adsorbent regeneration.
Solution Approach 2:
The patent replaces the mechanical vacuum system with a thermal field system. The vacuum regeneration process is substituted by heating the adsorbent bed with hot gas or steam, transforming the regeneration mechanism from mechanical (vacuum pressure differential) to thermal (temperature-driven desorption). This substitution eliminates complex vacuum equipment and reduces overall system complexity.
2Reliability
If reducing agents like hydrogen are used to regenerate the adsorbent, then oxygen can be removed effectively, but the operating costs increase due to the need for expensive chemicals
Solution Approach 1:
The patent enables the adsorbent to regenerate itself through thermal treatment without requiring external reducing agents. The oxygen adsorbed on the adsorbent is desorbed by heating, and the adsorbent returns to its original state automatically. This self-service regeneration eliminates the need for hydrogen or other chemical reducing agents, significantly reducing operating costs.
Solution Approach 2:
The patent converts the harmful effect of strongly adsorbed oxygen into a beneficial regeneration process. By heating the adsorbent bed, the strongly bound oxygen is desorbed and can be purged from the system. The thermal energy that would otherwise be wasted is converted into a useful regeneration mechanism, eliminating the need for expensive chemical reducing agents.
3Manufacturing precision
If large adsorbent beds are used to achieve low oxygen concentrations, then purification effectiveness improves, but the capital costs and space requirements increase
Solution Approach 1:
The patent changes the operating temperature parameter to enhance adsorption selectivity and capacity. By optimizing the adsorption temperature and using temperature swing for regeneration, the system achieves high purification effectiveness with a smaller adsorbent bed volume compared to isothermal processes.
Solution Approach 2:
The patent employs periodic temperature swing operation with multiple adsorbent beds. During one cycle, one bed is adsorbing oxygen while another is being regenerated by heating. This periodic operation allows continuous purification with smaller individual bed sizes, reducing total capital cost and space requirements while maintaining high oxygen removal effectiveness.
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 TSA process effectively reduces oxygen levels in liquid argon to below 1 part per million with reduced capital and operating costs, using smaller adsorbent beds and minimizing argon uptake, thus providing a more economical and efficient purification method suitable for large-scale ASU operations.
Implementation Method 1
adsorbing at least part of the oxygen on the adsorbent thereby producing a purified liquid argon product
Implementation Method 2
zeolites, however, are reversible physical adsorbents
Implementation Method 3
A Temperature Swing Adsorption (TSA) process using modified zeolite 4A adsorbents that regenerates by purging with warm nitrogen or argon streams above cryogenic temperatures
Implementation Method 4
desorbing at least part of the adsorbed oxygen and removing this from the inlet of the adsorbent bed
Implementation Method 5
indirectly cooling the adsorbent bed containing adsorbent, where the bed has an inlet and an outlet, as well as a direct and an indirect cooling means to a temperature below about 150 degrees Kelvin
Implementation Method 6
cooling the regenerated adsorbent within the bed is provided in order that the purification process can begin again
Data Source
Figure 1(A)~1(H)
AI summary
The invention relates to a process for removing oxygen from liquid argon using a TSA (temperature swing adsorption) cyclical process that includes cooling an adsorbent bed to sustain argon in a liquid phase; supplying the adsorbent bed with a liquid argon feed that is contaminated with oxygen and purifying the liquid argon thereby producing an argon product with less oxygen contaminant than is in the initial liquid argon feed; draining the purified residual liquid argon product and sending purified argon out of the adsorbent bed. Regeneration of specially prepared adsorbent allows the adsorbent bed to warm up to temperatures that preclude the use of requiring either vacuum or evacuation of adsorbent from the bed.