Air separation method and plant
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Solution Overview
Problem
In classical adsorption purifiers of cryogenic air separation units, existing air grid capacity may be insufficient for new units, leading to inefficient and unstable air flow control during switching steps, particularly when integrating additional air separation units into existing sites.
Innovation Solution
A combination of an air grid and a smaller main air compressor is used, with control strategies focusing on managing the main air compressor to maximize capacity without overloading the grid or losing air feed during pressurization, utilizing flow control valves and guide vanes to stabilize air flow, and measuring downstream air flow to adjust compressor settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a dedicated main air compressor is used for the complete air demand of the new air separation unit, then the air supply capacity is sufficient, but the device complexity and cost increase
Solution Approach 1:
The patent combines the air grid supply and dedicated main air compressor into a unified air supply system, where both sources feed into a common mixing point that supplies the air separation unit. This merging approach allows the system to achieve sufficient air supply capacity while avoiding the need for a completely separate dedicated compressor infrastructure.
Solution Approach 2:
The air grid serves multiple functions: it provides base air supply to existing units and can supplement the new air separation unit when needed. The dedicated main air compressor provides supplemental capacity specifically for the new unit. This multi-functional arrangement allows existing infrastructure to be reused while adding only the necessary supplemental capacity.
2Device complexity
If the existing air grid capacity is used with a smaller main air compressor, then the device complexity is reduced, but the air flow control stability deteriorates
Solution Approach 1:
The patent implements a control system that continuously monitors air flow parameters and adjusts the operation of the dedicated main air compressor accordingly. This feedback mechanism ensures that the combined air grid and compressor system maintains stable air flow control, compensating for the complexity reduction by adding intelligent control.
Solution Approach 2:
The system dynamically adjusts the contribution of each air source (air grid vs. dedicated compressor) based on real-time demands and conditions. The control system modulates the compressor operation to maintain stable total air flow to the mixing point, allowing the system to adapt to varying conditions while maintaining stability.
3Productivity
If control strategies focus on managing the main air compressor to maximize capacity, then the productivity increases, but the air feed loss during pressurization may occur
Solution Approach 1:
The control system performs preliminary actions by pre-regulating and stabilizing the air flow from the dedicated main air compressor before it reaches the air separation unit. This includes pre-cooling and pressure regulation, ensuring that the air is properly conditioned before admission, which prevents losses during the pressurization phase and maximizes effective capacity utilization.
Solution Approach 2:
The system maintains continuous and stable air supply to the air separation unit by coordinating the air grid and dedicated compressor operations. The control strategies ensure uninterrupted air feed during pressurization cycles, preventing losses that would occur with intermittent or unstable supply, thereby maintaining maximum productive operation.
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 ensures stable and efficient operation of air separation units by optimizing air flow distribution, utilizing existing grid capacity effectively and preventing air feed loss during pressurization, thereby enhancing operational efficiency and economic viability.
Implementation Method 1
the setting of the air flow at the outlet of the main air compressor is performed by controlling the guide vanes of the main air compressor
Implementation Method 2
the air flow from the air grid to the mixing point is set by a flow control valve
Implementation Method 3
The mixed air 6 is cooled in a classical direct contact cooler 7 by direct contact with cooling water
Implementation Method 4
The purifier is operated by TSA (temperature swing adsorption)
Implementation Method 5
The purifier is operated by TSA (temperature swing adsorption), PSA (pressure swing adsorption) or a combination of both
Data Source
Figure 1
Figure 2
AI summary
In this air separation method, compressed air (6) is successively cooled in a cooling step (7), purified in a purifier (9) and sent to a cryogenic section (11) producing at least one product containing at least one air component. The purifier (9) 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 (1) supplying compressed air to further consumers. The second source is a dedicated main air compressor (4) delivering compressed air to the cooling step (7) only. Air portions (2, 5) from both sources are mixed at a mixing point (3). The airflow (10) to the cryogenic section (11) is controlled by measuring (12, 12.1, 12.2) at least one parameter of the air flow upstream or downstream the purifier. According to such measurement, the air flow (5) at the outlet of the main air compressor (4) is set (14) .