Cryogenic Oxygen Separation Plant With Auxiliary Column Pressure Balancing
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Solution Overview
Problem
Large-capacity air separation plants for oxygen production are inefficient in terms of energy usage, particularly in plants handling air rates over 370,000 Nm3/h, as they require significant compression energy due to high pressures in the distillation column system.
Innovation Solution
The method involves a distillation column system with a high-pressure column, a low-pressure column, an argon discharge column, and an auxiliary column, where a portion of crude oxygen is supplied to the auxiliary column at an intermediate point, operating at a pressure 50 mbar higher than the low-pressure column, reducing the pressure difference and thus the energy required for compression, and allowing the nitrogen product to serve as regeneration gas, thereby disburdening the low-pressure column.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure is used in the distillation column system to increase oxygen production capacity, then productivity increases, but energy consumption increases due to significant compression energy requirements
Solution Approach 1:
The distillation column system is segmented into multiple columns operating at different pressures (first column at higher pressure, second column at lower pressure). This segmentation allows each column to operate in an optimized pressure range, reducing the overall compression energy required while maintaining high oxygen production capacity through the combined output of multiple columns.
Solution Approach 2:
The system changes the pressure parameter across different columns rather than operating all columns at a single high pressure. The first column operates at a higher pressure (3-10 bar) while the second column operates at a lower pressure (1-3 bar), allowing the system to achieve high productivity without proportionally high energy consumption for compression.
2Manufacturing precision
If a complex distillation column system with multiple columns is used to optimize separation efficiency, then manufacturing precision and separation quality improve, but device complexity increases
Solution Approach 1:
The separation process is segmented into multiple columns, each with a specific function (first column for initial separation at high pressure, second column for final separation at low pressure). This segmentation improves overall separation efficiency by allowing each column to be optimized for its specific separation task while maintaining manageable individual column designs.
Solution Approach 2:
The distillation column system is designed with multi-functionality where columns serve both separation functions and heat integration functions. The columns are equipped with heat exchangers that enable heat recovery between streams, allowing the same structural elements to perform multiple functions (separation, heating, cooling) thereby reducing overall device complexity despite the multi-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 configuration leads to a marked reduction in energy consumption by optimizing the pressure difference across the columns, increasing oxygen production capacity while maintaining similar column dimensions, and allowing the nitrogen product to be used for regeneration, enhancing the overall efficiency of the air separation process.
Implementation Method 1
the heat-exchanging relationship between the high-pressure column and the low-pressure column of a double column is generally realized by way of a main condenser, in which tops gas from the high-pressure column is liquefied against evaporating bottoms liquid from the low-pressure column
Implementation Method 2
the heat-exchanging relationship between the high-pressure column and the low-pressure column of a double column is generally realized by way of a main condenser, in which tops gas from the high-pressure column is liquefied against evaporating bottoms liquid from the low-pressure column
Implementation Method 3
The principles of low-temperature separation of air generally and the construction of two-column plants specifically are described in the monograph 'Tieftemperaturtechnik' [low-temperature technology] by Hausen/Linde
Implementation Method 4
The main condenser and the argon discharge column tops condenser are configured as condenser-evaporators. The condensation (liquefaction) of the first fluid stream takes place in the liquefaction space, the evaporation of the second fluid stream in the evaporation space. The evaporation space and the liquefaction space are formed by groups of passages which are in a heat-exchanging interrelationship.
Implementation Method 5
The evaporation space and the liquefaction space are formed by groups of passages which are in a heat-exchanging interrelationship
Data Source
AI summary
The plant is used for producing oxygen by cryogenic air separation. The plant has a high-pressure column, a low-pressure column and a main condenser. An argon-elimination column is in fluid connection with an intermediate point of the low-pressure column and is connected to an argon-elimination column head condenser. An auxiliary column has a sump region, into which gas is introduced from the argon-elimination column head condenser. The head of the auxiliary column is connected to a return flow liquid line, in order to introduce a liquid stream from the high-pressure column or the head condenser. The liquid stream has an oxygen content which is at least equal to that of air. At least one part of the crude liquid oxygen from the sump of the high-pressure column is fed to the auxiliary column at a first intermediate point.