Method and unit for low-temperature air separation
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Solution Overview
Problem
Current air separation methods, such as SPECTRA, face challenges in reducing energy consumption and improving material yield, particularly in producing high-purity gaseous nitrogen at a superatmospheric pressure level while also efficiently extracting additional nitrogen and argon products.
Innovation Solution
The proposed method involves a modified SPECTRA process with a double-column system, including a third rectification column operated at a pressure between the first and second columns, allowing for air feed into both the first and third columns, and utilizing a condenser evaporator in the sump region of the second column for energy-efficient operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional single-column SPECTRA method is used, then high-purity gaseous nitrogen at superatmospheric pressure can be produced, but energy consumption is high and material yield is limited
Solution Approach 1:
The air separation process is divided into multiple functional columns: a first rectification column for nitrogen production, a second rectification column for oxygen production, and a third rectification column for argon production. This segmentation allows each column to be optimized for its specific product, improving overall energy efficiency and material yield compared to a single-column system.
Solution Approach 2:
The condenser evaporator in the sump region of the second column serves multiple functions: it condenses nitrogen-rich gas from the first column, provides cooling for the oxygen production process, and enables efficient heat exchange between columns. This multi-functionality reduces the need for separate equipment and improves energy utilization.
2Productivity
If additional nitrogen and argon products are extracted, then material yield improves, but energy consumption increases
Solution Approach 1:
The system maintains continuous operation of all three rectification columns simultaneously, with the first column producing nitrogen, the second producing oxygen, and the third producing argon. The condenser evaporator enables continuous heat exchange and material transfer between columns, ensuring that all components are constantly contributing to product generation without idle periods, thereby maximizing material yield per unit of energy consumed.
Solution Approach 2:
Each rectification column operates at different pressure levels and temperature conditions optimized for its specific product. The first column operates at higher pressure for nitrogen, the second at lower pressure for oxygen, and the third at intermediate conditions for argon. These parameter optimizations allow simultaneous production of multiple products with reduced energy consumption compared to sequential processing.
3Use of energy by moving object
If a double-column system is used with a condenser evaporator, then energy efficiency improves, but device complexity increases
Solution Approach 1:
The condenser and evaporator functions are merged into a single integrated heat exchange unit located in the sump region of the second column. This combined unit simultaneously performs nitrogen condensation from the first column and provides cooling for the oxygen production process, eliminating the need for separate condenser and evaporator equipment and reducing overall system complexity despite the multi-column configuration.
Solution Approach 2:
The condenser evaporator utilizes the cold energy from the sump region of the second column to condense nitrogen-rich gas from the first column, and simultaneously uses the heat from this condensation process to support the oxygen production. This self-service heat exchange eliminates the need for external cooling utilities and reduces overall energy input requirements.
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 enhances the yield of argon and total energy efficiency, enabling the production of larger quantities of high-purity gaseous nitrogen at a superatmospheric pressure level while simultaneously producing lower quantities of argon in an energy-efficient manner.
Implementation Method 1
low-temperature separation of air in air separating installations... rectification column systems which can conventionally be designed, for example, as two-column systems... rectification columns for extracting nitrogen and/or oxygen in the liquid and/or gaseous state
Implementation Method 2
production of air products in the liquid or gaseous state by low temperature separation of air
Implementation Method 3
utilizing a condenser evaporator in the sump region of the second column for energy-efficient operations
Data Source
AI summary
The invention relates to a method for a low-temperature air separation in which an air separation unit is used comprising a first rectification column and a second rectification column. The first rectification column is operated at a first pressure level, and the second rectification column is operated at a second pressure level below the first pressure level. Fluid which is oxygen-enriched compared to atmospheric air is drawn from the first rectification column in the form of one or more first material flows. At least one fraction of the fluid which has been drawn from the first rectification column in the form of the one or more first material flows is heated in a heat exchanger; a fraction of the fluid which has been heated in the heat exchanger is compressed using a compressor and is returned to the first rectification column.