Container CA Air Control With Selective Nitrogen Supply
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Solution Overview
Problem
The existing inside air control system for containers fails to maintain a consistently low oxygen concentration, as the nitrogen-enriched air produced initially has a high oxygen concentration that gradually decreases, leading to an average oxygen concentration in the container that is not effectively controlled below the desired level.
Innovation Solution
The system alternates between adsorption and desorption operations in the adsorption columns to produce nitrogen-enriched air, with a partial supply operation where nitrogen-enriched air with high oxygen concentration is discharged, and only air with low oxygen concentration is supplied into the container, and adjusts the timing of nitrogen-enriched air discharge based on oxygen concentration levels to prioritize oxygen concentration reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the whole nitrogen-enriched air produced during desorption operation is supplied into the container, then the productivity of the system is improved, but the oxygen concentration control precision deteriorates because the initial nitrogen-enriched air has high oxygen concentration
Solution Approach 1:
The nitrogen-enriched air supply is divided into two segments: initial nitrogen-enriched air (discarded) and subsequent nitrogen-enriched air (supplied). This segmentation allows the system to exclude the portion with high oxygen concentration while utilizing the portion with low oxygen concentration, thereby resolving the contradiction between supply rate and concentration control precision
Solution Approach 2:
The system extracts and discards the initial nitrogen-enriched air that contains high oxygen concentration from the desorption operation. By removing this problematic portion, the system can supply only the subsequent nitrogen-enriched air with low oxygen concentration into the container, achieving precise oxygen concentration control
2Quantity of substance
If the desorption operation is performed to produce nitrogen-enriched air, then the oxygen concentration in the container is reduced, but the oxygen concentration fluctuates because the produced air has varying oxygen concentration over time
Solution Approach 1:
The system performs a preliminary action by discarding the initial nitrogen-enriched air before supplying it into the container. This preliminary discarding action removes the unstable portion with high oxygen concentration, ensuring that only the stable portion with low oxygen concentration is supplied, thereby achieving stable oxygen concentration control
Solution Approach 2:
The system maintains continuous supply of nitrogen-enriched air with low oxygen concentration by discarding only the initial portion and continuously supplying the subsequent portions. This continuous supply of stable composition air ensures stable oxygen concentration control in the container
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 precise control of oxygen concentration in the container, ensuring it remains lower than the average oxygen concentration of the nitrogen-enriched air produced, effectively maintaining a fresh environment for perishable goods.
Implementation Method 1
an adsorbent which adsorbs a nitrogen component in the air when pressurized is used to produce nitrogen-enriched air having a lower oxygen concentration and a higher nitrogen concentration than the air
Implementation Method 2
performs a desorption operation of sucking the air using the air pump from the adsorption column to allow the adsorbent to desorb the nitrogen component adsorbed
Data Source
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AI summary
Disclosed herein is a CA system (60) which allows first and second adsorption columns (34, 35) to alternately perform an adsorption operation and a desorption operation so that nitrogen-enriched air having a higher nitrogen concentration and a lower oxygen concentration than the air is produced and supplied into the container (11). The CA system (60) executes a second operation mode in which the nitrogen-enriched air produced for a predetermined time since the desorption operation was started is discharged to the outside of the container (11), and the nitrogen-enriched air produced until the end of the desorption operation since the predetermined time passed is supplied into the container (11).