Supercritical Water CO2 Capture Process
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Solution Overview
Problem
Current CO2 capture processes in thermal power plants are energy-intensive, reducing the efficiency and profitability of fossil fuel-fired power plants, and often rely on additional fossil fuel consumption to enhance CO2 absorption efficiency.
Innovation Solution
Integrating a biofuel boiler into the CO2 capture system, where exhaust gas from the power plant is used as an oxygen-containing gas for combustion, increasing CO2 concentration and reducing oxygen levels, thereby enhancing CO2 absorption efficiency and reducing energy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CO2 capture is carried out using conventional aqueous amine absorbents in thermal power plants, then CO2 separation is achieved, but the efficiency of the thermoelectric power plant is reduced and energy consumption increases
Solution Approach 1:
The patent changes the fundamental parameter of the absorbent from conventional aqueous amine solutions to supercritical water. This parameter change enables CO2 capture at higher temperatures (above 374°C, the critical temperature of water), eliminating the need for energy-intensive steam stripping regeneration. The supercritical water absorbent achieves high CO2 solubility and selective absorption without requiring the high energy input needed for conventional amine regeneration.
Solution Approach 2:
The patent uses supercritical water as a copy or alternative to conventional amine absorbents, achieving similar CO2 absorption functionality through a different medium. Supercritical water replicates the CO2 capture function of amines but with superior energy efficiency and no need for external heating during regeneration.
2Reliability
If conventional amine absorbents are used for CO2 capture, then CO2 removal is achieved, but additional fossil fuel consumption is required to generate steam for regeneration
Solution Approach 1:
The supercritical water absorbent system is self-sufficient and does not require external steam injection for regeneration. The system uses the process itself (cooling and pressure control) to regenerate the absorbent, eliminating the need for separate steam generation and injection steps that consume additional fossil fuel energy in conventional systems.
Solution Approach 2:
The patent exploits phase transitions of water (liquid to supercritical fluid and back) to achieve CO2 capture and release. By controlling temperature and pressure, water transitions to a supercritical state for high-capacity CO2 absorption, then returns to liquid state for automatic CO2 release and absorbent regeneration, eliminating the need for steam-based regeneration.
3Device complexity
If exhaust gas is directly used for CO2 absorption, then the process is simple, but CO2 concentration is low and absorption efficiency is reduced
Solution Approach 1:
The patent changes the temperature parameter of the exhaust gas by cooling it to subcritical temperatures (below 374°C) before absorption. This temperature reduction increases CO2 solubility in the supercritical water absorbent, significantly improving absorption efficiency while maintaining process simplicity. The cooling step is integrated into the existing flue gas handling system.
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 approach increases CO2 capture efficiency and reduces energy consumption in the CO2 capture process, allowing for more CO2 to be absorbed at lower energy costs, potentially achieving negative CO2 emissions by utilizing biofuel combustion as an environmentally neutral energy source.
Implementation Method 1
The exhaust gas from the power plant is cooled, compressed and used as an oxygen containing gas
Implementation Method 2
the gas mixture to be separated is introduced countercurrent to the aqueous adsorbent in an absorber column
Implementation Method 3
heat has to be supplied to the regenerator column to reverse the absorption and release the CO2
Data Source
AI summary
A method and a plant for capturing CO2 from an exhaust gas from combustion of carbonaceous material are described. At least a part of the combustion gas is introduced into a biol fuel boiler as an oxygen containing gas, to increase the concentration of CO2 and decrease the oxygen concentration in the gas before introduction into an absorption column for separation of CO2.