Electrolytic Scrubber Regeneration for Lower-Energy CO2 Capture
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Solution Overview
Problem
Current CO2 scrubbing technologies, particularly those using aqueous monoethanolamine, are energy-intensive and costly, making them inefficient for large-scale carbon capture from coal-fired power plants, with a need for more energy-efficient and cost-effective solutions.
Innovation Solution
A method involving an alkaline, aqueous scrubbing liquid that uses electrolysis to regenerate the spent scrubbing solution, converting hydrogen carbonate and carbonate back into carbon dioxide and oxygen, reducing the energy consumption and increasing the pH for efficient CO2 capture, and utilizing the generated hydrogen and oxygen for additional value-added processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aqueous monoethanolamine is used for CO2 scrubbing, then CO2 capture capability is improved, but energy consumption increases significantly
Solution Approach 1:
The patent changes the chemical composition parameter of the scrubbing solution from aqueous monoethanolamine to an alkaline aqueous solution (such as potassium hydroxide or sodium hydroxide). This parameter change fundamentally alters the regeneration mechanism from thermal decomposition to electrochemical regeneration, thereby reducing energy consumption while maintaining CO2 capture capability.
Solution Approach 2:
The patent replaces the thermal regeneration system (heating) with an electrochemical regeneration system (electrolysis). By substituting the thermal field with an electrical field, the regeneration process consumes significantly less energy, directly resolving the contradiction between CO2 capture capability and energy consumption.
2Productivity
If aqueous monoethanolamine scrubbing is used, then CO2 removal efficiency is improved, but operational costs increase
Solution Approach 1:
The patent changes the chemical parameter of the scrubbing agent from amine-based to alkaline hydroxide-based solution. This parameter change enables electrochemical regeneration which has lower operational costs compared to the high thermal energy requirements of amine scrubbing, thereby reducing operational costs while maintaining CO2 removal efficiency.
Solution Approach 2:
The patent substitutes the thermal regeneration process with electrochemical regeneration. This substitution reduces operational costs by eliminating the need for high-temperature heating systems and associated fuel costs, while the electrolytic cell provides a more economically viable regeneration pathway.
3Use of energy by moving object
If spent scrubbing liquid is regenerated by electrolysis, then energy consumption is reduced, but pH increase must be controlled for efficient CO2 capture
Solution Approach 1:
The patent implements a feedback control mechanism where the pH of the regenerated scrubbing liquid is monitored and the electrolysis process parameters are adjusted accordingly. By controlling the extent of electrolysis and the composition of the alkaline solution, the pH is optimized to the appropriate range for efficient CO2 capture, resolving the contradiction between energy reduction and pH optimization.
Solution Approach 2:
The patent carefully controls the concentration parameters of the alkaline solution and the electrolysis conditions to achieve the desired pH range. By adjusting these parameters, the system maintains optimal pH for CO2 capture while benefiting from the lower energy consumption of electrochemical 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
This approach significantly reduces energy consumption, lowers operational costs, and enables efficient CO2 capture from flue gases, with the potential to utilize the produced hydrogen and oxygen for electricity generation and synthesis of organic compounds, such as methanol, thereby compensating for the process costs.
Implementation Method 1
scrubbing of the flue gas using a chemical absorption medium, such as an alkaline, aqueous liquid. In an alkaline, aqueous liquid, CO2 will dissolve and partly be hydrolyzed into carbonic acid (H2CO3). Given the alkaline pH, formed carbonic acid (H2CO3) will be shifted into hydrogen carbonate (HCO3−) and/or carbonate (CO32−)
Implementation Method 2
CO2 will dissolve and partly be hydrolyzed into carbonic acid (H2CO3)
Implementation Method 3
The first spent aqueous scrubbing liquid is fed to an anode chamber of an electrolytic cell with an anode and a cathode. In the electrolytic cell, the first spent aqueous scrubbing liquid is regenerated by electrolysis. In electrolysis, water is converted into oxygen and hydronium ions (H3O+) at the anode, whereas water is converted into hydrogen and hydroxide ions (OH−) at the cathode
Implementation Method 4
The anode and the cathode of the electrolytic cell are separated by a membrane to provide the anode chamber and a cathode chamber. The membrane is permeable to alkali metals, such as lithium, sodium and potassium, but has no or low permeability to hydrogen carbonate (HCO3−) and/or to carbonate (CO32). Typically, the membrane is permeable only to cations. The membrane may be a cation-exchange membrane.
Data Source
AI summary
A method of scrubbing a gas, such as flue gas or exhaust gas, comprising carbon dioxide to deplete the gas of carbon dioxide (CO2), the method comprising the steps of: —scrubbing the gas in a scrubber (210) with a first alkaline, aqueous scrubbing liquid to dissolve carbon dioxide (CO2) as hydrogen carbonate (HCO3<sup2>−</sup2>) and/or as carbonate (CO32-) in the first alkaline, aqueous scrubbing liquid, thereby providing a first spent aqueous scrubbing liquid comprising hydrogen carbonate (HCO3—) and/or carbonate (CO32-), the first spent aqueous scrubbing liquid having a pH from about 7 to about 9; —feeding the first spent aqueous scrubbing liquid to an anode chamber of an electrolytic cell (310) comprising the anode chamber (313) and a cathode chamber (312) separated by a membrane (311); —regenerating the first spent aqueous scrubbing liquid in the electrolytic cell (310) by electrolysis, the electrolysis increasing the pH of the first spent aqueous scrubbing liquid in the cathode chamber (312), the electrolysis further depleting the first spent aqueous scrubbing liquid of hydrogen carbonate (HCO3—) and of carbonate (CO32-) in the anode chamber (313) by decreasing the pH, the regeneration further comprising generating gaseous hydrogen in the cathode chamber (312) and a gaseous mixture of oxygen and carbon dioxide (CO2) in the anode chamber (313) by electrolysis; and—withdrawing regenerated alkaline, aqueous scrubbing liquid from the cathode chamber (312) and re-circulating it to the scrubber (210); wherein: —the gaseous hydrogen is withdrawn from the cathode chamber (312); and—the gaseous mixture of oxygen and carbon dioxide is withdrawn from the anode chamber (313).