Amine-Selexol Absorbent for Selective SO2 Capture
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Solution Overview
Problem
Existing sulfur dioxide (SO2) capture technologies require significant energy for regeneration, particularly for stripping absorbed SO2 from the absorbing medium, which contributes substantially to the operating costs of SO2 removal processes.
Innovation Solution
A process involving an aqueous lean absorbing medium comprising a chemical solvent, a physical solvent, and heat stable salts, where the medium is contacted with a feed gas stream to selectively absorb SO2, allowing for reduced energy consumption during regeneration by using steam stripping and optimizing the ratios of physical solvent to regenerable absorbent and heat stable salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam stripping is used to regenerate the absorbing medium, then SO2 can be removed from the spent absorbing medium, but significant energy is consumed in the process
Solution Approach 1:
The patent uses a composite absorbing medium containing both a chemical solvent (amine-based) and a physical solvent (selexol). The chemical solvent provides high SO2 absorption capacity through chemical reaction, while the physical solvent enhances SO2 solubility and facilitates easier desorption during regeneration. This composite approach allows effective SO2 removal while reducing the energy required for steam stripping regeneration compared to using chemical solvents alone.
2Quantity of substance
If a chemical solvent is used to absorb SO2, then high absorption capacity is achieved, but CO2 is also removed along with SO2
Solution Approach 1:
The patent exploits the different solubility characteristics of SO2 and CO2 in the physical solvent component. SO2 has much higher solubility in the physical solvent (selexol) compared to CO2, allowing the absorbing medium to selectively preferentially absorb SO2 over CO2. This local quality difference in solubility enables selective SO2 capture while minimizing CO2 removal from the gas stream.
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 reduces regeneration energy consumption by 10% or more, achieving selective SO2 removal while minimizing the removal of CO2 and other components, and maintaining a single liquid phase throughout the process.
Implementation Method 1
contacting the feed gas stream with an aqueous lean absorbing medium to absorb sulfur dioxide
Implementation Method 2
stripping absorbed SO2 from the spent absorbing medium to produce a regenerated aqueous absorbing medium and a gaseous SO2
Data Source
AI summary
A process for removing sulfur dioxide from a feed gas stream, which comprises (i) contacting the feed gas stream with an aqueous lean absorbing medium comprising a chemical solvent comprising a regenerable absorbent, a physical solvent, and one or more heat stable salts. The regenerable absorbent is an amine. The ratio of the wt % of the physical solvent over that of the regenerable absorbent is 0.5 to 2.5. The ratio of the wt % of heat stable salts over that of the regenerable absorbent is 0.29 to 0.37. The pH of the lean absorbing medium is 6 or less. With the process SO2 can be selectively removed. When the absorbing medium is stripped, a reduced amount of energy is required as compared to known processes.