Method and apparatus for producing air products
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Solution Overview
Problem
Existing methods for producing krypton/xenon mixtures and oxygen from air separation units face inefficiencies in recovering high-purity oxygen and krypton/xenon mixtures, particularly due to their accumulation in liquid oxygen and the need for additional enrichment steps.
Innovation Solution
A method involving a two-stage rectification process using first and second rectification columns, where the second fraction enriched in oxygen is introduced into the second column to produce high-purity oxygen, and a third column for further refinement, allowing recovery of high-purity oxygen and krypton/xenon mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rectification column arrangements are used to produce krypton/xenon mixtures, then krypton and xenon can be accumulated in liquid oxygen, but high-purity oxygen recovery is inefficient and additional enrichment steps are required
Solution Approach 1:
The rectification process is divided into multiple columns with distinct functions: the first column separates oxygen from krypton/xenon mixture, the second column purifies oxygen to high purity, and the third column further refines the oxygen product. This segmentation allows each column to specialize in a specific separation task, achieving high-purity oxygen recovery without requiring excessive complexity in any single unit
Solution Approach 2:
The invention introduces a vertical arrangement of multiple rectification columns operating in sequence, adding a dimensional aspect to the separation process. Instead of relying on a single complex column, the system uses a series of columns stacked in functional sequence, where each column contributes to the overall purification cascade, thereby achieving high purity through cumulative separation effects
2Quantity of substance
If conventional air separation units process considerable amounts of air to obtain krypton and xenon, then noble gases can be accumulated in liquid oxygen, but the process is inefficient and time-consuming
Solution Approach 1:
The first rectification column performs preliminary separation by removing the bulk of oxygen from the air separation unit output, concentrating krypton and xenon in a smaller volume of liquid oxygen. This preliminary action prepares the material for more efficient processing in subsequent columns, reducing the overall processing time and increasing productivity
Solution Approach 2:
The invention implements a continuous multi-column rectification process where the output of one column continuously feeds into the next. The first column continuously produces oxygen-depleted liquid oxygen, which is continuously processed by the second column, which in turn feeds the third column. This continuous operation eliminates idle time between processing stages, significantly improving production efficiency
3Manufacturing precision
If additional enrichment steps are introduced to improve oxygen purity, then high-purity oxygen can be recovered, but the device complexity and processing time increase
Solution Approach 1:
Each rectification column operates at optimized parameters (temperature, pressure, feed composition) tailored to its specific separation function. The first column operates with parameters optimized for bulk oxygen removal, the second column uses parameters optimized for high-purity oxygen production, and the third column applies final refinement parameters. These parameter optimizations minimize processing time at each stage while achieving the required overall purity
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 method enables the recovery of high-purity oxygen and krypton/xenon mixtures by enhancing the separation process, improving the yield and quality of oxygen products.
Implementation Method 1
The production of air products in liquid or gaseous state by cryogenic separation of air in air separation units is well known
Implementation Method 2
The feed mixture or a part thereof is subjected to a rectification (first rectification column) providing a first fraction depleted in oxygen and enriched in krypton and xenon
Implementation Method 3
The lower part of the first rectification column may be electrically heated
Data Source
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Figure 5
AI summary
A method and an apparatus for producing air products comprising the steps of providing a feed mixture (201) comprising krypton, xenon and oxygen, introducing the feed mixture (201) into a first rectification column (121), withdrawing a first fraction (202) depleted in oxygen and enriched in krypton and xenon relative to the feed mixture (201) and a second fraction (203) enriched in oxygen and depleted in krypton and xenon relative to the feed mixture (1) from the first rectification column (121), introducing a third fraction (204) derived from the second fraction (203) into a second rectification column (125) and withdrawing a high-purity oxygen fraction (O) from the second rectification column (125).