Method and device for the low-temperature separation of air at variable energy consumption
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Solution Overview
Problem
Air separation plants using High Air Pressure (HAP) processes face challenges in maintaining efficient operation across varying production levels, particularly when oxygen demand fluctuates, as the energy demand is heavily influenced by oxygen production, leading to limitations in producing other air separation products during reduced oxygen output.
Innovation Solution
A method and device that incorporate a multi-stage compressor system and air turbine expansion to manage air compression and energy distribution efficiently, allowing for variable operation by adjusting the amount of feed air and using a second air turbine to optimize heat exchange, enabling flexible energy use across different production modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the entire feed air is compressed to a high pressure in a main air compressor to enable internal compression of product streams, then the energy consumption for compression is reduced and the process is simplified, but the system loses flexibility to adapt to variable oxygen demand and production levels
Solution Approach 1:
The air compression system is segmented into a main air compressor for bulk compression and a booster compressor for additional compression of specific streams. This segmentation allows the main compressor to operate at optimal efficiency while the booster provides flexible adjustment capability to meet varying oxygen demand without compromising overall energy efficiency.
Solution Approach 2:
The system incorporates variable geometry diffusers and adjustable guide vanes in the compressor stages, allowing dynamic adjustment of compression characteristics. This enables the system to adapt to different operating conditions and oxygen demand levels while maintaining efficient compression performance across a range of loads.
2Device complexity
If a single main air compressor is used to compress all feed air to high pressure, then device complexity is reduced, but the system cannot efficiently handle variable production levels and other air separation products suffer
Solution Approach 1:
The multi-stage compressor system with intermediate cooling stages serves multiple functions: it compresses feed air to high pressure for internal compression, provides flexible flow distribution to different process streams, and enables efficient heat exchange at multiple pressure levels. This multi-functionality allows a single compressor system to handle both oxygen product variation and other air separation products simultaneously.
Solution Approach 2:
The system introduces an intermediary booster compressor stage that acts as a mediator between the main compression system and the distillation columns. This intermediary component provides the necessary flexibility and pressure adjustment capability without requiring complete system redesign, thereby maintaining relatively simple overall complexity while enabling variable production operation.
3Manufacturing precision
If the system operates at constant high compression pressure to maintain separation efficiency, then nitrogen-oxygen separation performance is optimized, but energy consumption increases during low oxygen demand periods
Solution Approach 1:
The system dynamically changes compression parameters including pressure ratios, flow rates, and intercooling temperatures based on oxygen demand. During low demand periods, the compression pressure and flow are reduced while maintaining sufficient separation efficiency, thereby avoiding energy waste. The parameter adjustments are coordinated with distillation column operation to preserve separation performance.
Solution Approach 2:
The compressor system operates in periodic cycles that alternate between high-compression modes during high oxygen demand and reduced-compression modes during low demand. This periodic adjustment of compression intensity allows the system to maintain separation efficiency when needed while minimizing energy consumption during low-demand periods, creating an optimized operational rhythm.
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 allows for consistent production of other air separation products with reduced energy consumption, maintaining efficiency across a wide load range and minimizing the impact of fluctuating oxygen demand on overall plant performance.
Implementation Method 1
a first partial stream of the feed air compressed in the main air compressor is cooled down to an intermediate temperature in a main heat exchanger and expanded in a first air turbine in such a way that work is performed
Implementation Method 2
a first partial stream of the feed air compressed in the main air compressor is cooled down to an intermediate temperature in a main heat exchanger
Implementation Method 3
The distillation column system of such a plant may be formed as a two-column system (for example as a classic Linde double-column system), or else as a three- or multi-column system. In addition to the columns for nitrogen-oxygen separation
Implementation Method 4
a first product stream is removed in a liquid form from the distillation column system and subjected to a pressure increase to a first product pressure, the first product stream is evaporated or pseudo-evaporated under the first product pressure
Data Source
AI summary
A method and device used to variably obtain a compressed-gas product by means low-temperature separation of air in a distillation column system. In a first operating mode, a first amount of first compressed-gas product is obtained, and, in a second operating mode, a second, smaller amount is obtained. In the first operating mode, a first amount of air is compressed in the main air compressor, and in the second operating mode, a second, larger amount is compressed in the main air compressor.