SOx Capture Using Cooled Alkaline Carbonate Solution
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Solution Overview
Problem
Conventional CO2 capture processes face efficiency losses due to the absorption of SOx and NOx contaminants, which lead to precipitation and reduced absorption capacity in alkaline solutions, requiring frequent solution bleeding and replacement, and generate waste products.
Innovation Solution
A process and system that integrates SOx removal from flue gases using a cooled alkaline carbonate solution, where the gas is contacted with an alkaline aqueous solution containing a carbonate of an alkali metal, allowing for SOx absorption and subsequent purification of the solution, reducing the need for frequent bleeding and waste disposal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional alkaline absorption solutions are used for CO2 capture, then CO2 absorption capacity is achieved, but SOx and NOx contaminants are also absorbed causing precipitation and reduced absorption capacity
Solution Approach 1:
The absorption process is divided into two separate functional units: a gas conditioning unit for SOx/NOx removal and a CO2 absorption unit for carbon capture. This segmentation prevents contaminants from affecting the CO2 absorption solution, maintaining both absorption capacity and solution stability without requiring frequent bleeding or replacement.
Solution Approach 2:
A cooled alkaline carbonate solution is introduced as an intermediary medium in the gas conditioning unit. This intermediary selectively removes SOx and NOx contaminants from the flue gas before the cleaned gas enters the CO2 absorption unit, thereby protecting the CO2 absorption solution from contamination and precipitation issues.
2Object-affected harmful factors
If SOx removal is performed using conventional technologies as auxiliary units, then SOx levels are reduced, but device complexity increases and integration with CO2 capture process is lacking
Solution Approach 1:
The SOx removal function and CO2 absorption function are merged into a single integrated process system. The cooled alkaline carbonate solution serves dual purposes: it conditions the gas by removing SOx/NOx and prepares it for subsequent CO2 capture. This merging reduces device complexity compared to separate auxiliary units while effectively reducing SOx concentration.
3Quantity of substance
If absorption solution bleeding is performed to maintain absorption capacity, then absorption solution quality is preserved, but loss of substance increases and operational costs rise
Solution Approach 1:
SOx and NOx contaminants are removed in advance in the gas conditioning unit before the gas enters the CO2 absorption unit. This preliminary action prevents contamination of the absorption solution, eliminating the need for bleeding to maintain solution quality and thereby reducing absorption solution consumption and operational costs.
4Productivity
If flue gas is cooled before CO2 absorption, then absorption efficiency is improved, but water vapour condensation occurs and may cause precipitation
Solution Approach 1:
SOx and NOx contaminants are removed before the cooling and CO2 absorption steps. By eliminating these contaminants in advance, the harmful effect of precipitation formation during cooling is prevented, allowing the gas to be cooled efficiently to improve CO2 absorption without suffering from precipitation issues.
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 SOx removal efficiency, reduces the environmental impact, and minimizes the consumption of alkaline solutions, thereby improving CO2 capture performance and reducing operational costs by recycling waste streams and utilizing sulfates as a by-product.
Implementation Method 1
contacting, in a treatment unit, the gas with a cooled alkaline aqueous solution comprising water and a carbonate of an alkali metal... thereby causing... absorption of the SOx in the carbonate-containing solution
Implementation Method 2
contacting, in a treatment unit, the gas with a cooled alkaline aqueous solution... having a temperature lower than the initial gas temperature, thereby causing cooling of the gas, condensation of some water vapour
Data Source
AI summary
A desulfurization gas process includes water vapor, CO2 and SOx (x=2 and/or 3). In a treatment unit, the gas contacts a cooled alkaline aqueous solution having a temperature lower than an initial gas temperature, water and a carbonate of an alkali metal, to cool the gas, condense some water vapor and absorb SOx in the carbonate-containing solution, produce an SOx-depleted gas and an acidic aqueous solution including sulfate and/or sulfite ions. The SOx-depleted gas and a portion of the acidic aqueous solution can then be withdrawn from the treatment unit. Carbonate of the alkali metal can be added to remaining acidic aqueous solution to obtain a made-up alkaline aqueous solution. This solution can be cooled and reused as the cooled alkaline aqueous solution. An SOx absorbent solution includes a bleed stream from a CO2-capture process, sodium or potassium carbonate, and an acidic aqueous solution obtained from desulfurization.