Process and plant for low-temperature separation of air
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Solution Overview
Problem
Existing air separation processes struggle to efficiently produce large quantities of nitrogen with high purity and elevated pressure alongside certain quantities of impure oxygen, particularly for applications in semiconductor manufacturing and glass production, as existing plants often fail to provide pure oxygen efficiently.
Innovation Solution
A three-column air separation process is introduced, where the first rectification column operates at 9 to 13.5 bar, the second at 5.5 to 8.5 bar, and the third at 1.1 to 2.5 bar, utilizing condenser-evaporators and decompression machines to manage cooling capacity and produce high-pressure nitrogen and impure oxygen products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional two-column air separation system is used, then nitrogen can be produced at elevated pressure, but the production of impure oxygen with desired efficiency is not achieved
Solution Approach 1:
The air separation system is divided into three distinct rectification columns operating at different pressure levels: a first column at 9-13.5 bar for high-pressure nitrogen production, a second column at 5.5-8.5 bar, and a third column at 1.1-2.5 bar for impure oxygen production. This segmentation allows each column to be optimized for its specific product, resolving the contradiction between nitrogen quantity and oxygen production efficiency.
2Stress or pressure
If the first rectification column operates at high pressure (9-13.5 bar), then nitrogen is produced at elevated pressure suitable for semiconductor manufacturing, but the cooling capacity requirements increase
Solution Approach 1:
The second rectification column operates as an intermediary at a medium pressure level (5.5-8.5 bar), receiving liquid from the first high-pressure column and transferring processed liquid to the third low-pressure column. This intermediary column acts as a pressure buffer, allowing the first column to operate at high pressure for nitrogen production without directly coupling the high pressure to the cooling capacity requirements of the final oxygen product.
3Productivity
If a three-column system is implemented with different pressure levels, then both high-purity nitrogen and impure oxygen can be produced efficiently, but the device complexity increases
Solution Approach 1:
The second rectification column serves multiple functions: it receives liquid from the first column, performs partial rectification, and supplies liquid to the third column. It acts as both a pressure buffer and a rectification stage, making the system more efficient despite the increased number of columns. The multi-functional design justifies the added complexity by improving overall productivity.
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 process achieves efficient production of high-purity nitrogen at elevated pressure and impure oxygen with reduced cooling capacity requirements, enhancing overall efficiency and meeting specific product demands.
Implementation Method 1
head gas of the first rectification column is condensed and liquid from the second rectification column or liquid formed herefrom is evaporated
Implementation Method 2
liquid from the second rectification column or liquid formed herefrom is evaporated
Implementation Method 3
a first condenser-evaporator, which in particular can be the main condenser connecting the first and the second rectification column in a heat-exchanging manner
Implementation Method 4
a first portion of the further liquid from the second rectification column evaporated by means of the second condenser-evaporator is decompressed, heated and removed from the process
Implementation Method 5
a first portion of the further liquid from the second rectification column evaporated by means of the second condenser-evaporator is decompressed, heated and removed from the process
Implementation Method 6
rectification columns for extracting nitrogen and/or oxygen in the liquid and/or gaseous state, i.e., rectification columns for nitrogen-oxygen separation
Implementation Method 7
production of air products in the liquid or gaseous state by cryogenic fractionation of air in air separation plants
Data Source
AI summary
Described herein is a process for low-temperature separation of air, in which an air separation plant having a first rectification column and a second rectification column is used, the first rectification column being supplied with cooled compressed air and the second rectification column being supplied with liquid from the first rectification column or liquid formed herefrom. In a first condenser-evaporator, head gas from the first rectification column is condensed and liquid from the second rectification column, or liquid formed herefrom, is evaporated, thereby producing a first evaporation product.