Method for obtaining a liquid and a gaseous oxygen-rich air product in an air breakdown apparatus and air breakdown apparatus
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Solution Overview
Problem
Conventional air separation plants with mixing columns have limited operational flexibility, restricting the production of liquid and gaseous oxygen-rich air products due to the limited cooling capacity and pressure differences between high-pressure and low-pressure columns, which limits the withdrawal quantity of liquid nitrogen and oxygen to about 0.5% of the air used.
Innovation Solution
The method involves an air separation plant with a main heat exchanger and a distillation column system comprising a high-pressure column, a low-pressure column, and a mixing column, where oxygen-rich streams with different oxygen contents are managed to optimize energy use and flexibility by expanding air in multiple turbines and feeding compressed air streams into different columns, allowing for the efficient production of both gaseous and liquid oxygen-rich products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air is expanded in an injection turbine to meet cooling requirements, then cooling capacity is improved, but the rectification process is disrupted and operational flexibility is limited
Solution Approach 1:
The invention divides the air expansion function into two separate turbines: a first turbine for expanding air to a first pressure level (e.g., 5-6 bar) and a second turbine for expanding air to a second pressure level (e.g., 1.2-1.6 bar). This segmentation allows independent optimization of each expansion stream, enabling the first turbine to provide cooling without disrupting the low-pressure column rectification, thus improving both cooling capacity and operational flexibility.
2Productivity
If the amount of air expanded in the injection turbine is increased to extract more liquid products, then liquid production quantity is improved, but the rectification process is severely disrupted
Solution Approach 1:
By segmenting the expansion function into two turbines with different pressure levels, the invention allows the first turbine to expand air to a higher pressure that can be fed to the high-pressure column without disrupting the low-pressure column rectification. This enables increased liquid product extraction while maintaining stable rectification processes in both columns.
Solution Approach 2:
The high-pressure column acts as an intermediary system that receives expanded air from the first turbine and performs rectification at the higher pressure level before feeding to the low-pressure column. This intermediary high-pressure column absorbs the impact of expanded air on the rectification process, allowing greater flexibility in liquid product extraction while maintaining low-pressure column stability.
3Device complexity
If a single pressure level system is used, then device complexity is reduced, but the ability to produce both liquid and gaseous oxygen-rich products efficiently is limited
Solution Approach 1:
The invention segments the air separation system into high-pressure and low-pressure columns, each operating at optimized pressure levels for different product requirements. The first turbine expands air to the high-pressure level for the high-pressure column, while the second turbine expands air to the low-pressure level for the low-pressure column. This segmentation enables efficient production of both liquid and gaseous oxygen-rich products while maintaining manageable system complexity through modular design.
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 significantly increases the flexibility and efficiency of producing oxygen-rich air products, enabling the discharge of liquid oxygen-rich products in larger quantities and optimizing energy consumption by adjusting the air factor and pressure levels, thereby enhancing the operational flexibility and reducing costs.
Implementation Method 1
expanded in a first turbine to a first pressure level
Implementation Method 2
expanded in a second turbine to a second pressure level
Implementation Method 3
cooled in the main heat exchanger
Implementation Method 4
cryogenic separation of air in air separation plants
Implementation Method 5
The oxygen-rich liquid is thereby vaporized within the mixing column
Implementation Method 6
a certain proportion of the more volatile nitrogen from the mixing column air transfers into the oxygen-rich liquid
Data Source
Figure 1
AI summary
A method for the low-temperature separation of air is proposed, in which an air separation plant (100) with a main heat exchanger (3) and a distillation column system (6, 7) is used, which has a high-pressure column (61) operated at a first pressure level, a high-pressure column (61) at a second , Lower pressure level operated low-pressure column (62) and a mixing column (7). A first stream of compressed air (h) is fed in gaseous form into the mixing column (7), in particular immediately above the bottom, and sent in the mixing column (7) in the opposite direction to an oxygen-rich stream (n). The first compressed air stream (h) is formed using air that is compressed to an initial pressure level above the first pressure level and then cooled to a first temperature level and expanded in a first turbine (4). A second compressed air stream (g) is fed into the high-pressure column (62), which is also formed using the air compressed to the initial pressure level and then cooled to the first temperature level and expanded in the first turbine (4). On the other hand, a third compressed air stream (f) is fed into the low-pressure column (62), which is formed using air that is also compressed to the initial pressure level, but is then cooled to a second temperature level, expanded in a second turbine (4) and in the main heat exchanger (3) is further cooled to a third temperature level. The air in the first turbine (4) is expanded to the first and the air in the second turbine (5) to the second pressure level. The air expanded in the first and second turbine (4, 5) is fed to the first turbine (4) on the first and second turbine (5) at the second temperature level, with the first temperature level being at least 20 K below the second. The mixing column (7) is operated at the first pressure level or a third pressure level, which differs from the first pressure level by at most 1 bar. A liquid oxygen-rich air product is discharged from the air separation unit (100) in the liquid state. A corresponding air separation plant (100) is also the subject of the present invention.