Air Separation Plant Flow Control Using Dual Compressed Air Sources
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Solution Overview
Problem
Existing air grids may not provide sufficient capacity for additional air separation units, necessitating the use of a dedicated main air compressor, and controlling the total air flow in such systems is inefficient and unstable.
Innovation Solution
Control the main air compressor independently, using flow control valves and guide vanes to manage air flow from both sources, with measurements downstream the purifier to stabilize the total air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a dedicated main air compressor is used to provide complete air demand for the new air separation unit, then the air capacity requirement is met, but the device complexity and cost increase
Solution Approach 1:
The patent combines air from two sources (existing air grid and new main air compressor) into a single mixed air stream that supplies the air separation unit. This merging approach allows the system to meet total air capacity requirements while avoiding the need for a single large, complex compressor by utilizing the existing air grid infrastructure alongside a smaller dedicated compressor.
2Productivity
If air flow from air grid and main air compressor are mixed, then the air separation unit can operate with maximum capacity, but the control stability deteriorates
Solution Approach 1:
The patent implements a control system that continuously monitors the mixed air flow to the air separation unit and uses this feedback information to adjust the flow contribution from each source (air grid and main air compressor). This feedback mechanism ensures stable operation by dynamically balancing the two air sources according to actual demand, preventing fluctuations that would otherwise occur from mixing variable air flows.
3Device complexity
If flow control valve for air grid is positioned fixed, then the control system is simplified, but the adaptability to varying air demand decreases
Solution Approach 1:
The patent employs a dynamic control strategy where the main air compressor's guide vanes are actively adjusted based on real-time feedback from flow measurements, while the air grid flow control valve maintains a fixed position. This dynamic adjustment of the compressor side compensates for the static nature of the grid valve, allowing the system to adapt to varying air demands through the controllable compressor portion while keeping the overall control system relatively simple.
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
Ensures stable and efficient operation of air separation units by maximizing capacity utilization without overloading the grid, using a smaller main air compressor in combination with the grid.
Implementation Method 1
a main air compressor (4) being e.g. a turbocompressor. Pressurized air from the main air compressor (4) is guided by line (5) to the mixing point (3)
Implementation Method 2
The mixed air (6) is cooled in a classical direct contact cooler (7) by direct contact with cooling water
Implementation Method 3
The purifier is operated by TSA (temperature swing adsorption), PSA (pressure swing adsorption) or a combination of both
Implementation Method 4
The purifier is operated by TSA (temperature swing adsorption), PSA (pressure swing adsorption) or a combination of both
Data Source
AI summary
In this air separation method, compressed air is successively cooled in a cooling step, purified in a purifier and sent to a cryogenic section producing at least one product containing at least one air component. The purifier comprises at least two switchable adsorber vessels, one of them being in adsorption mode. Two sources of compressed air are provided. The first source is an air grid supplying compressed air to further consumers. The second source is a dedicated main air compressor delivering compressed air to the cooling step only. Air portions from both sources are mixed at a mixing point. The air flow to the cryogenic section is controlled by measuring at least one parameter of the air flow upstream or downstream the purifier. According to such measurement, the air flow at the outlet of the main air compressor is set.