Acid Washing Section for CO2 Capture Emission Control
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Solution Overview
Problem
Existing CO2 capture processes using aqueous amine solutions face challenges in controlling degradation product emissions, particularly ammonia, during changes in operating conditions, as water washing may be insufficient to maintain regulatory compliance.
Innovation Solution
Implementing an acid washing section downstream of the CO2 capture process, monitored by operating parameter variations, to anticipate and mitigate peak emissions of degradation products, and reduce their content in the absorbent solution without atmospheric release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If water washing is used to remove degradation products, then the system is simple and economical, but it cannot control emission peaks during transient operating phases
Solution Approach 1:
The system dynamically switches between water washing and acid washing modes based on real-time monitoring of degradation product emissions. During normal operation, water washing is used for simplicity. When transient phases are detected (start-up, shutdown, load changes), the system automatically activates acid washing to control emission peaks, then returns to water washing when emissions are controlled.
Solution Approach 2:
The invention changes the chemical parameter of the washing solution from neutral water to acidic solution during transient phases. This parameter change enables the acid washing section to effectively capture basic degradation products like ammonia that water alone cannot remove, thereby controlling emissions during critical operating transitions.
2Reliability
If acid washing is implemented continuously, then emission peaks are controlled, but economic costs increase due to acid consumption and system complexity
Solution Approach 1:
Instead of continuous acid washing, the system uses periodic acid washing only during transient phases when emission peaks are detected. The acid washing section is activated temporarily during start-up, shutdown, or load change events, and deactivated during steady-state operation. This periodic operation maintains emission control reliability while significantly reducing acid consumption and system complexity.
Solution Approach 2:
The system employs real-time monitoring of degradation product emissions to provide feedback on washing performance. Based on this feedback, the control system automatically activates or deactivates the acid washing section, ensuring it operates only when necessary to control emission peaks, thereby optimizing both reliability and economic performance.
3Reliability
If water washing capacity is oversized to handle emission peaks, then regulatory compliance is maintained, but economic costs increase
Solution Approach 1:
The washing system is segmented into two functional sections: a water washing section for normal operation and an acid washing section for transient phases. This segmentation allows each section to be optimized for its specific function, with the acid washing section being smaller and activated only when needed, rather than requiring the entire system to be oversized for peak handling.
Solution Approach 2:
The control system acts as an intermediary that monitors emission parameters and mediates between the water washing section and acid washing section. It decides when to activate the acid washing section based on real-time conditions, allowing the system to handle emission peaks without requiring permanent oversized capacity in the water washing section.
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
Effectively controls ammonia emissions within regulatory limits during transient phases, ensuring continuous compliance and reducing the need for oversized water washing systems, while minimizing economic and environmental impacts.
Implementation Method 1
The acid used to lower the pH of the aqueous solution is chosen so as to react totally with the basic compounds
Implementation Method 2
Absorption processes using an aqueous amine solution are commonly used to remove the CO2 from a gas
Implementation Method 3
the absorbent solution is thermally regenerated
Implementation Method 4
The latter are generally present in small quantities, but can have a high vapor pressure
Data Source
Figure 1
Figure 2
AI summary
The carbon dioxide contained in combustion fumes is absorbed by an aqueous solution of amines in section B1. The decarbonated fumes are then scrubbed with water in scrubbing section B3. To prevent the emission of amine degradation products with the decarbonated fumes, the process operation is monitored, and an acidic flue gas scrubbing section U is implemented when the operating conditions of the carbon dioxide capture process require it.