Staged Amine Feed in Post-Combustion CO2 Capture to Cut Regeneration Energy
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Solution Overview
Problem
Existing carbon capture technologies for natural gas combined cycle (NGCC) flue gases face challenges in achieving high CO2 capture efficiency with minimal absorbent degradation and energy penalty, while also requiring significant solvent regeneration energy and reduced solvent loading.
Innovation Solution
A staged absorbent regeneration process with staged CO2-lean and CO2-rich amine absorbent inlets, combined with a controlled temperature profile and heat integration, utilizing direct contact cooling and reboiler condensate return, to enhance CO2 capture efficiency and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-stage amine absorbent regeneration is used, then the system is simpler to operate, but CO2 capture efficiency is reduced and absorbent degradation increases
Solution Approach 1:
The patent divides the single-stage absorbent regeneration system into multiple stages, where CO2-rich amine absorbent is fed to the stripper at different levels (third and fourth inlets) and CO2-lean absorbent is returned to the absorber at different levels (first and second inlets). This segmentation allows for optimized mass transfer and temperature control in each stage, achieving 95%+ CO2 capture efficiency while managing absorbent degradation through controlled staged regeneration.
2Productivity
If high solvent loading is used to maximize CO2 capture, then CO2 capture efficiency improves, but solvent regeneration energy requirement increases
Solution Approach 1:
The patent optimizes the loading parameters of the amine absorbent by controlling the staged feed rates and temperatures. By adjusting the absorbent loading levels and distribution across different stripper inlets, the system achieves high CO2 capture efficiency (95%+) while minimizing the energy required for regeneration through optimized mass transfer and heat integration.
Solution Approach 2:
The system utilizes heat integration where the CO2-rich absorbent stream serves to preheat the incoming CO2-lean absorbent, and the stripper reboiler condensate is returned to provide additional heating. This self-service heat recovery reduces the external energy requirement for solvent regeneration while maintaining high CO2 capture efficiency.
3Productivity
If absorber temperature is increased to improve mass transfer, then CO2 capture rate improves, but absorbent degradation increases and energy penalty increases
Solution Approach 1:
The patent applies different temperature conditions to different sections of the absorber by implementing staged absorbent feeds at different levels (first and second inlets). This allows the lower section to operate at higher temperatures for improved mass transfer while the upper section operates at lower temperatures to minimize absorbent degradation, achieving optimized CO2 capture rate with preserved absorbent stability.
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 system achieves 95%+ CO2 capture efficiency with minimal absorbent degradation and energy penalty, optimizing solvent loading and reducing solvent regeneration energy requirements, thereby improving overall plant efficiency and reducing capital and operating costs.
Implementation Method 1
the amine reacts with the CO2 to form a carbamate or bicarbonate salt along with a protonated amine to balance the overall charge
Implementation Method 2
Reboilers adapted to provide heat to strip the CO2 from the rich solvent
Implementation Method 3
a cooler adapted for condensing liquids from captured CO2 discharged from the captured CO2 outlet
Implementation Method 4
a first pump and first conduit system adapted for delivering CO2-rich amine absorbent from a CO2-rich amine absorbent outlet in the absorber to the staged CO2-rich amine absorbent inlet
Implementation Method 5
a second pump and second conduit system adapted for delivering a CO2-lean amine absorbent from a CO2-lean absorbent outlet of the stripper to the staged CO2-lean amine absorbent inlet
Data Source
AI summary
An apparatus for capturing carbon dioxide (CO2) from a gas stream includes an absorber having (a) a flue gas inlet and (b) a staged CO2-lean amine absorbent inlet, including a first inlet and a second inlet at different levels of the absorber. The apparatus also includes: a stripper, including a staged CO2-rich amine absorbent inlet having a third inlet and a fourth inlet; a first pump and first conduit system adapted for delivering CO2-rich amine absorbent from a CO2-rich amine absorbent outlet in the absorber to the staged CO2-rich amine absorbent inlet; and a second pump and second conduit system adapted for delivering a CO2-lean amine absorbent from a CO2-lean amine absorbent outlet in the stripper to the staged CO2-lean amine absorbent inlet.