VOC Purification via Concentrated Saline Absorption
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Solution Overview
Problem
Industrial installations, such as fruit stations, face challenges in purifying VOC-laden gas streams to meet regulatory discharge limits, as current methods fail to effectively reduce VOC emissions into the atmosphere and purification stations.
Innovation Solution
A method involving the contact of VOC-laden gas streams with a highly concentrated saline solution, followed by decantation to separate and recover the VOCs, utilizing a countercurrent absorption process in a packed tower, and subsequent recirculation and adjustment of the saline solution, along with optional contact with a water stream to further purify the gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional purification methods are used for VOC-laden gas streams, then the discharge limits are exceeded, but the cost of implementation and complexity increase
Solution Approach 1:
The invention changes the parameter of salt concentration in the absorption liquid to at least 300 g/l, which fundamentally alters the properties of the system. This high salt concentration enables selective absorption of VOCs while maintaining phase separability, resolving the contradiction by achieving effective purification without requiring complex multi-stage systems
Solution Approach 2:
The invention utilizes phase separation based on density differences between the saline solution and organic phase. After absorption, the mixture undergoes phase transition where the organic phase separates and can be easily decanted, providing a simple yet effective method to achieve discharge compliance without complex separation equipment
2Ease of manufacture
If highly concentrated saline solution is used for absorption, then VOC recovery is simplified through decantation, but the cost of salt and complexity of solution management increase
Solution Approach 1:
The invention recycles the saline solution after phase separation. The organic phase is decanted and can be recovered or disposed of, while the saline solution is returned to the absorption system. This closed-loop approach reduces the quantity of salt needed over time and simplifies VOC recovery operations
Solution Approach 2:
The system performs self-service through automatic phase separation based on density differences. The high salt concentration creates sufficient density difference that allows gravitational separation without additional energy input or complex equipment, making the recovery process inherently simple and cost-effective
3Productivity
If the saline solution concentration is increased to improve VOC absorption efficiency, then the separation of phases becomes more difficult, but without sufficient concentration the absorption efficiency is inadequate
Solution Approach 1:
The invention identifies an optimal parameter range for salt concentration (at least 300 g/l) that simultaneously achieves high VOC absorption efficiency and maintains adequate phase separability. This precise parameter control resolves the contradiction by finding the sweet spot where both requirements are satisfied
Solution Approach 2:
The high concentration saline solution acts as an intermediary medium that facilitates both absorption and separation. Its unique properties at 300 g/l concentration allow it to absorb VOCs effectively while maintaining sufficient density difference for easy phase separation, mediating between the two contradictory requirements
4Reliability
If multiple purification stages are implemented to meet discharge limits, then the purification effectiveness increases, but the cost and energy consumption increase
Solution Approach 1:
The invention extracts the essential function of VOC removal into a single high-efficiency absorption stage using concentrated saline solution. By concentrating the absorption capability in one stage rather than using multiple lower-efficiency stages, the system achieves equivalent or superior purification effectiveness with lower energy consumption
Solution Approach 2:
The invention uses phase separation as a passive, energy-free separation mechanism. After absorption, the organic phase naturally separates and can be removed by simple decantation without requiring energy-intensive distillation or other separation processes, reducing overall energy consumption while maintaining high purification effectiveness
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 method effectively reduces VOC emissions to comply with legal limits, is cost-effective due to simple decantation-based recovery, and maintains a stable saline solution concentration for continuous operation.
Implementation Method 1
a step for placing the laden gas stream in contact with a saline solution stream, at least part of the quantity of volatile organic compound being extracted from the laden gas stream and absorbed by the saline solution stream
Implementation Method 2
a step for recovering the volatile organic compound, comprising a sub-step for decanting a laden saline solution stream, leading to the separation of a phase containing the volatile organic compound and of the saline solution
Data Source
AI summary
The purification method comprises:a step for placing the laden gas stream in contact with a saline solution stream, the saline solution stream comprising, before placement in contact, at least 300 g/l of salts, at least part of the quantity of volatile organic compound being extracted from the laden gas stream and absorbed by the saline solution stream, the placement in contact step producing a purified gas stream containing a residual quantity of volatile organic compound and a laden saline solution stream;a step for recovering the volatile organic compound, comprising a sub-step for decanting a laden saline solution stream, leading to the separation of a phase containing the volatile organic compound and of the saline solution.