Absorption-Desorption Decoupling for Low-Energy Flue Gas CO2 Capture
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Solution Overview
Problem
Existing carbon capture and storage technologies for coal-fired flue gas face high investment and operating costs, energy inefficiencies, and complexity due to separate systems for contaminant and CO2 removal, with challenges in absorbent regeneration and separation, limiting their widespread application.
Innovation Solution
A low-cost, high-efficiency absorption-desorption decoupling method for synergistic contaminant-CO2 capture, utilizing a multi-cycle absorption system with decoupled control units for each cycle, optimized by a database and penalty function to manage operating parameters, achieving independent control of contaminant and CO2 absorption, and reducing energy consumption through saturation-based desorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional chemical absorption method is used for CO2 capture, then CO2 removal efficiency is improved, but energy consumption increases significantly
Solution Approach 1:
The absorption column is divided into multiple cycles (first-cycle contaminant absorption section, second-cycle CO2 absorption section, third-cycle CO2 absorption section, fourth-cycle water washing section), each with independent control units. This segmentation allows different sections to operate at different conditions optimized for their specific function, reducing overall energy consumption while maintaining high CO2 removal efficiency of 90%.
Solution Approach 2:
The patent implements dynamic control of absorption parameters including pH values, temperatures, and liquid-gas ratios for each cycle section. The control units independently adjust these parameters in real-time based on operating conditions, enabling the system to maintain optimal performance across varying loads and fuel types, achieving 99% contaminant removal efficiency while minimizing energy use.
2Reliability
If separate systems are used for contaminant removal and CO2 capture, then each function can be optimized independently, but system complexity increases and operating costs rise
Solution Approach 1:
The patent combines contaminant removal and CO2 capture functions into a single integrated absorption-desorption system. The multi-cycle absorption column simultaneously performs both functions: the first cycle removes contaminants (SO2, NOx), while the second and third cycles capture CO2. This merging eliminates the need for separate processing systems, reducing overall system complexity and operating costs while maintaining high reliability for both functions.
Solution Approach 2:
The absorption system is designed with multi-functionality, where the same absorption column and absorbent can handle multiple pollutants (contaminants and CO2) through different operational cycles. The decoupling control system enables the universal apparatus to switch between different absorption modes, achieving both contaminant removal (99% efficiency) and CO2 capture (90% efficiency) with a single integrated system.
3Productivity
If high absorption capacity is achieved by increasing absorbent concentration, then capture efficiency improves, but desorption energy consumption increases
Solution Approach 1:
The patent applies local quality by using different absorbent concentrations and compositions in different cycle sections. The first-cycle contaminant absorption uses absorbent optimized for acid gas removal, while the second and third-cycle CO2 absorption sections use absorbent formulated for carbon capture. This localized optimization allows high capture efficiency in each section without requiring uniformly high absorbent concentration throughout, thereby reducing the energy penalty during desorption to below 2.7 GJ/t CO2.
Solution Approach 2:
The system dynamically changes absorption parameters including absorbent concentration, pH, and temperature across different cycles and operating conditions. By adjusting these parameters locally in each section rather than maintaining constant high values system-wide, the patent achieves high capture efficiency while minimizing the energy required for desorption and absorbent regeneration.
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 method achieves contaminant removal efficiency of 99% and CO2 removal efficiency of 90% with desorption energy consumption below 2.7 GJ/t CO2, simplifying the process flow and reducing energy costs while maintaining high capture efficiency.
Implementation Method 1
flue gas enters an absorption system which includes a multi-cycle absorption column... first-cycle contaminant absorption section, a second-cycle CO2 absorption section...
Implementation Method 2
rich liquid enters a desorption system which includes a desorption column via a lean-rich liquid heat exchanger... desorption energy consumption below 2.7 GJ/t CO2
Implementation Method 3
rich liquid enters a desorption system which includes a desorption column via a lean-rich liquid heat exchanger
Data Source
AI summary
The invention relates to a low-cost and high-efficiency absorption-desorption decoupling method for contaminant-CO2 synergistic capture. According to the method, an optimization model of absorption-desorption decoupling control for contaminant-CO2 synergistic capture under different working conditions is built, the optimization objective is to obtain high-purity liquid contaminants and CO2 at low cost and efficiently, and an adaptive penalty function is constructed to transform a solution of a constrained optimization problem into that of an unconstrained optimization problem, thereby controlling parameters in a real-time, precise and stable manner. Moreover, supported by means of flue gas pre-scrubbing and cooling, multi-stage intercooling and column-top demisting, the method of the present invention achieves efficient capture of contaminants and CO2. According to the invention, the absorption process is decoupled from the desorption process, and the coordinated control of temperature-pH-liquid-gas ratio and rich liquid flow-desorption temperature in all cycles is carried out to realize the synergistic capture-regeneration-concentration of contaminants and CO2 with high efficiency and low energy consumption, thereby reducing the high cost of the traditional method where a flue gas cleaning system and a carbon capture system operate separately.