Method and device for producing gaseous compressed oxygen having variable power consumption
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Solution Overview
Problem
Air separation plants face challenges in efficiently adjusting energy consumption due to fluctuating electricity tariffs, requiring a method that can operate variably with minimal equipment and maintain efficient oxygen production.
Innovation Solution
The method involves using two parallel-connected booster compressors to adjust air flow and energy consumption, allowing for reduced energy use by feeding in liquid oxygen and reducing cold production, with the option to switch off the turbine flow, and utilizing existing equipment to maintain consistent gaseous oxygen production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the air separation plant operates at full capacity to meet oxygen demand, then oxygen production is sufficient, but energy consumption is high
Solution Approach 1:
The patent implements dynamic operation modes that allow the air separation plant to adapt its capacity to match actual oxygen demand and electricity pricing conditions. The system can switch between full-capacity operation and reduced-capacity operation, dynamically adjusting compressor speeds, turbine flows, and distillation column operations to optimize the balance between oxygen production and energy consumption based on real-time conditions
Solution Approach 2:
The patent changes key operational parameters including compressor speed, turbine expansion ratio, distillation column pressure and temperature profiles, and heat exchanger flow rates to enable variable operation modes. By adjusting these parameters, the system can operate at different capacity levels while maintaining separation efficiency, thereby reducing energy consumption when full oxygen production is not required
2Use of energy by moving object
If the air separation plant reduces operation to lower energy consumption, then energy costs decrease, but oxygen production becomes insufficient
Solution Approach 1:
The patent uses preliminary action by storing liquid oxygen in advance during periods of low electricity demand or low pricing. This stored liquid oxygen serves as a buffer that can be quickly vaporized and delivered when oxygen demand increases or electricity prices rise, allowing the plant to operate at reduced capacity during charging periods while still meeting demand during discharge periods
3Use of energy by moving object
If quick load adjustment is implemented to respond to electricity price fluctuations, then energy cost optimization improves, but equipment complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing equipment that serves multiple purposes: the liquid oxygen storage tank functions both as a product storage facility and as a buffer for load adjustment; the heat exchanger network serves both cooling and heating functions across different operation modes; the compressor and turbine system can operate in compression mode, expansion mode, or bypass mode. This multi-functionality reduces the need for dedicated equipment for each function, thereby limiting the increase in overall equipment complexity
4Use of energy by moving object
If liquid oxygen is fed into the system to reduce air intake, then energy consumption decreases, but the system requires additional equipment for liquid oxygen handling
Solution Approach 1:
The patent applies self-service by using the plant's own produced liquid oxygen (from periods of high production) to feed back into the system during periods of reduced operation. The liquid oxygen storage tank, which would otherwise be a separate product storage facility, serves the dual purpose of storing product and providing feedstock for the distillation column. This self-service approach eliminates the need for external liquid oxygen sources and minimizes additional equipment 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 enables a wide range of energy consumption variation with up to 50% reduction in energy consumption during low-energy supply conditions while maintaining consistent gaseous oxygen production, with minimal hardware changes and low hardware effort.
Implementation Method 1
Methods and devices for the low-temperature separation of air are known, for example, from Hausen/Linde, Tieftemperaturtechnik, 2nd edition 1985, Chapter 4 (pages 281 to 337). The distillation column system can be designed as a two-column system (for example as a classic Linde double-column system)
Implementation Method 2
Methods and devices for the low-temperature separation of air
Implementation Method 3
During the process, a pressurized liquid oxygen product stream is evaporated against a heat transfer medium and finally obtained as a gaseous pressurized product
Implementation Method 4
Against the (pseudo-)evaporating product stream, a heat transfer medium under high pressure is liquefied (or pseudo-liquefied if it is under supercritical pressure)
Implementation Method 5
Occasionally this flow is also called throttle flow, although it can also be expanded in a liquid turbine (DFE = 'dense fluid expander') instead of a throttle valve
Data Source
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AI summary
The invention relates to a method and to a device for the variable production of compressed oxygen by means of low-temperature separation of air in a distillation column system which comprises a high-pressure column (5) and a low-pressure column (6). Process air in form of a total air stream (1) is cooled in a main heat exchanger (3). At least a part of the cooled process air is fed into the high-pressure column (5). A first oxygen stream (35) from the low-pressure column (6) is brought to an elevated pressure (36) in a liquid state, is vaporized, or pseudo-vaporized, and heated in the main heat exchanger (3), and is finally obtained as a gaseous compressed oxygen product. Prior to entering the main heat exchanger (3), a first and a second partial stream (12) of the process air are brought to a high pressure (9, 10), which is at least 4 bars higher than the operating pressure of the high-pressure column (5). The first partial stream is liquefied, or pseudo-liquefied, in the main heat exchanger (3), and is subsequently introduced into the distillation column system (14). The second partial stream (16) is expanded to perform work (17), and is subsequently introduced into the distillation column system (4). In a first operating mode, a first total air quantity is cooled in the main heat exchanger (3), and a first turbine amount as first partial stream (16) is fed to the expansion to perform work. In a second operating mode, a second oxygen stream (46) from an external source outside the distillation column system is introduced into the low-pressure column (6) in a liquid state. There is less total air (1) cooled in the main heat exchanger (3), and less air is fed to the expansion (17) to perform work than in the first operating mode.