Air separation method and apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current air separation methods in distillation column units face challenges in maximizing oxygen and argon recovery due to limitations in the liquid to vapor ratio within the lower pressure column, which affects the efficiency of oxygen and argon extraction as products.
Innovation Solution
The method involves producing a cryogenic rectification process with a first liquid stream having a higher oxygen content and a second liquid stream with a lower oxygen content and an argon content, where the second liquid stream is subcooled through indirect heat exchange and introduced into the lower pressure column above the crude liquid oxygen introduction point, increasing the liquid to vapor ratio and enhancing oxygen and argon recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid air is introduced into the lower pressure column above the crude liquid oxygen introduction point, then the liquid to vapor ratio below the introduction point increases and oxygen recovery increases, but the degree of oxygen removal from column overhead is limited
Solution Approach 1:
The patent applies parameter changes by subcooling the liquid air feed stream to a temperature below its dew point. This temperature parameter change causes the liquid stream to generate significantly less vapor upon introduction into the column, thereby increasing the liquid to vapor ratio and improving both oxygen recovery and removal efficiency from column overhead.
Solution Approach 2:
The patent applies preliminary action by pre-subcooling the liquid air stream before it is introduced into the lower pressure column. This preliminary cooling action modifies the physical state of the feed stream, enabling it to achieve the desired effect of increasing liquid to vapor ratio without requiring larger column dimensions or additional processing stages.
2Quantity of substance
If the liquid to vapor ratio in the lower pressure column is increased to improve oxygen and argon recovery, then more equipment or larger column size is required, increasing device complexity
Solution Approach 1:
The patent resolves this contradiction by changing the temperature parameter of the liquid air feed stream through subcooling. This parameter change increases the liquid to vapor ratio in situ, achieving higher oxygen and argon recovery without requiring larger column dimensions or additional equipment. The subcooled liquid generates less vapor upon introduction, effectively increasing the liquid phase availability for mass transfer and product recovery within the existing column configuration.
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 increases oxygen production and recovery by reducing oxygen in the column overhead and accumulating more argon in the lower sections of the lower pressure column, thereby enhancing the overall recovery of both oxygen and argon.
Implementation Method 1
the second liquid stream is subcooled through indirect heat exchange with the first liquid stream
Implementation Method 2
compressed and purified air is distilled within a distillation column unit
Implementation Method 3
a cryogenic rectification process is conducted that comprises distilling compressed and purified air into at least a nitrogen-rich fraction and oxygen-rich fraction
Implementation Method 4
the crude liquid oxygen stream introduced into the lower pressure column for further refinement into an oxygen-rich liquid column bottoms and a nitrogen-rich vapor column overhead. The lower pressure column operates at a lower pressure to enable the oxygen-rich liquid to condense at least part of the nitrogen-rich vapor column overhead
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A cryogenic air separation method and apparatus in which first (68) and second (64) liquid streams are produced. The first liquid stream (68) has a higher oxygen content than air and can consist of a higher pressure distillation column bottoms and the second liquid stream (64), for instance, air, has a lower oxygen content than the first liquid stream and an argon content no less than the air. The second liquid stream (64) is subcooled through indirect heat exchange (118) with the first liquid stream (138) and both of such streams are introduced into the lower pressure column (30). The second liquid stream (152) is introduced into the lower pressure column (30) above that point at which the crude liquid oxygen column bottoms or any portion thereof (140,146,148) is introduced into the lower pressure column to increase a liquid to vapor ratio below the introduction of the second liquid stream and therefore, reduce the oxygen present within the column overhead (94).