Alkaline Scrubber Liquid Regeneration for CO2 Capture
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Solution Overview
Problem
Existing CO2 scrubbing technologies, particularly those using aqueous amines, are energy-intensive and costly, limiting their implementation in large-scale applications such as coal-fired power plants and ships, and require substantial water transport, making them inefficient and impractical for vehicles like ships.
Innovation Solution
A method involving the use of an alkaline, aqueous scrubbing liquid with a pH of at least 12, comprising alkali metal hydroxides like KOH, to dissolve CO2 as hydrogen carbonate and carbonate, followed by precipitation of hydrogen carbonate as a solid, decoupling the absorption from the regeneration process, allowing for efficient CO2 capture and simplified transport of captured CO2 as a solid alkali metal hydrogen carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aqueous amines are used for CO2 scrubbing, then CO2 absorption occurs, but the process becomes energy-consuming and costly
Solution Approach 1:
The patent changes the chemical composition parameter of the scrubbing liquid from aqueous amines to alkaline aqueous solutions (such as potassium hydroxide or sodium hydroxide). This parameter change fundamentally alters the absorption mechanism and eliminates the energy-intensive regeneration step required by amine systems, as alkaline solutions can be regenerated through simple heating or electrolysis without requiring high-energy steam stripping.
2Adaptability or versatility
If buffer tanks are provided for storing regenerated and spent scrubber liquid, then decoupling of regeneration and scrubbing is enabled, but the tanks become very large for ships
Solution Approach 1:
The patent extracts the regeneration process from the ship and relocates it to a central land-based facility. The ship only carries the compact alkaline scrubbing liquid and returns with concentrated CO2-rich spent liquid for regeneration. This extraction eliminates the need for large onboard buffer tanks and regeneration equipment, while still providing process decoupling benefits through the central facility that serves multiple vessels.
3Quantity of substance
If transport of substantial amounts of water is performed, then CO2 capture is enabled, but efficiency is reduced and practicality is limited
Solution Approach 1:
The patent changes the concentration parameter of the alkaline scrubbing liquid to optimize the water-to-CO2 ratio. By using concentrated alkaline solutions (such as 1-5 M KOH or NaOH), the system minimizes the volume of water that needs to be transported and processed while maintaining effective CO2 absorption capacity, thereby improving logistical efficiency for mobile applications.
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 enhances CO2 absorption efficiency, reduces the need for large scrubbers and water transport, and enables efficient CO2 capture on vehicles and ships by allowing regeneration at a central location, thus optimizing operational costs and logistics.
Implementation Method 1
removing the CO2 from the gas stream by absorbing/dissolving CO2 in a liquid
Implementation Method 2
CO2 will dissolve and partly be hydrolyzed into carbonic acid (H2CO3)
Implementation Method 3
the process disclosed in WO 2022/096644 has been shown to be highly efficient, there is still a need for further improvements to such a process
Implementation Method 4
precipitating hydrogen carbonate (HCO3-) from the spent aqueous scrubbing liquid as a solid
Data Source
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AI summary
A method of scrubbing a gas (106), comprising carbon dioxide to deplete the gas (106) of carbon dioxide (CO2). The method comprises the steps of: - scrubbing the gas in a scrubber (200) with a first alkaline, aqueous scrubbing liquid (101), comprising an alkali metal cation (M+), the first aqueous scrubbing liquid (101) having a pH of at least 12, to dissolve carbon dioxide (CO2) in the first alkaline aqueous scrubbing liquid (101) as hydrogen carbonate (HCO3-) and carbonate (CO32-), thereby providing a spent aqueous scrubbing liquid (102) comprising hydrogen carbonate (HCO3-) and carbonate (CO32-), wherein the spent aqueous scrubbing (102) liquid has a pH of at least 8, and wherein the spent aqueous scrubbing liquid (102) has a first temperature; - precipitating hydrogen carbonate (HCO3-) as alkali metal hydrogen carbonate (MHCO3) in the spent aqueous scrubbing liquid (102); - separating an aqueous solution comprising dissolved carbonate (CO32-), the aqueous solution having reduced content of hydrogen carbonate (HCO3-), from precipitated alkali metal hydrogen carbonate (MHCO3), to provide a second alkaline, aqueous scrubbing liquid (103) comprising carbonate (CC32-) and alkali metal cation (M); and - at least partly using the second alkaline, aqueous scrubbing liquid (103) in scrubbing the gas (106) in the scrubber (200).