Multi-Stage Chilled Ammonia CO2 Capture System
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Solution Overview
Problem
Current chilled ammonia-based CO2 capture systems for flue gas streams face inefficiencies due to ammonia slip and high operational costs, requiring large absorber vessels and significant refrigeration capacity, which are not effectively addressed by single-stage systems.
Innovation Solution
A multi-stage CO2 capture system using multiple absorber vessels with controlled ionic solution flows and temperatures to minimize ammonia slip, optimizing the ammonia-to-CO2 mole ratio and operating temperatures across different stages for enhanced CO2 capture efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage chilled ammonia system is used, then the system structure is simple, but CO2 capture efficiency is low and ammonia slip is high
Solution Approach 1:
The absorption process is divided into three distinct stages with different ionic solution temperatures and compositions. The first stage uses a warmer solution for initial CO2 removal, the second stage uses a chilled solution for enhanced capture, and the third stage optimizes for ammonia slip minimization. This segmentation allows each stage to be optimized for its specific function, achieving high overall efficiency while maintaining reasonable system complexity.
2Volume of stationary object
If a single-stage chilled ammonia system is used, then the equipment size is small, but significant refrigeration capacity is required
Solution Approach 1:
The refrigeration load is segmented across three absorption stages, with each stage handling a portion of the CO2 capture at different temperatures. This distributes the refrigeration demand over time and allows heat integration between stages, reducing the peak refrigeration capacity required compared to a single-stage system achieving the same total CO2 removal.
Solution Approach 2:
The system changes the temperature parameter of the ionic solution across different stages. By using warmer solution in the first stage and progressively colder solution in subsequent stages, the system optimizes the balance between absorption efficiency and refrigeration energy consumption, achieving effective CO2 capture with reduced overall refrigeration capacity requirements.
3Productivity
If ammonia-to-CO2 mole ratio is increased, then CO2 capture efficiency improves, but ammonia slip increases
Solution Approach 1:
The ammonia-to-CO2 mole ratio is optimized differently in each absorption stage. The first stage uses a moderate ratio to achieve initial CO2 removal with minimal ammonia slip, while subsequent stages use progressively optimized ratios to maximize CO2 capture efficiency. This staged optimization allows the system to achieve high overall CO2 removal while minimizing total ammonia slip compared to using a high ratio throughout.
Solution Approach 2:
Different local conditions (ammonia-to-CO2 mole ratios and temperatures) are applied in different absorption stages to optimize both CO2 capture efficiency and ammonia slip minimization simultaneously, rather than using uniform conditions throughout the system.
4Ease of manufacture
If operational costs are reduced, then economic viability improves, but CO2 capture efficiency may decrease
Solution Approach 1:
The three-stage absorption process segments the CO2 removal task to optimize operational costs. By distributing the capture efficiency requirements across stages with different ionic solution conditions, the system achieves high overall CO2 removal while minimizing the total amount of chilled ionic solution required, thereby reducing energy consumption and operational costs compared to single-stage systems.
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
The multi-stage system achieves higher CO2 capture efficiency, reduces ammonia slip, and decreases operational costs by optimizing the ammonia-to-CO2 mole ratio and temperature control across stages, allowing for more effective CO2 removal from flue gas streams.
Implementation Method 1
contacting a first ionic solution flow with a flue gas stream to remove a first portion of CO2 from the flue gas stream
Implementation Method 2
cooling the third ionic solution flow so as to minimize ammonia slip from the ionic solution
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An ammonia based CO2 capture system and method is provided in which multiple absorption stages (272, 274 and 276) are provided. Each absorption stage (272, 274 and 276) delivers an ionic solution at a predetermined temperature (T) and contacts it with a flue gas stream (FG).