Amine Solvent System for CO2 Capture Mass Transfer
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Solution Overview
Problem
Current CO2 capture technologies face challenges in maximizing mass transfer rates and minimizing energy requirements, particularly in post-combustion CO2 capture, where flue gas is at near-atmospheric pressure and CO2 concentration is low, leading to high energy costs and inefficient processes.
Innovation Solution
A solvent system comprising a promoter amine with a pKa between 6.5 and 10.5 and a tertiary amine with a pKa between 8.5 and 10.5, combined with water, is used to enhance CO2 capture by increasing mass transfer rates without increasing volatility or viscosity, thereby reducing amine loss and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If primary and secondary amines are used to achieve high mass transfer rate, then the absorber size is reduced, but the regeneration energy increases due to high enthalpy of absorption
Solution Approach 1:
The invention divides the amine system into two functional components: a promoter amine (primary or secondary) that enhances mass transfer rate, and a tertiary amine that provides low regeneration energy. This segmentation allows each component to specialize in one function, resolving the contradiction between high productivity and low energy consumption.
Solution Approach 2:
The invention creates a composite amine system by combining promoter amine and tertiary amine in specific ratios. This composite approach synergistically integrates the advantages of both amine types: the promoter amine accelerates CO2 absorption kinetics while the tertiary amine maintains low heat of regeneration, achieving both high mass transfer rate and low regeneration energy.
2Productivity
If promoter amine is added to increase mass transfer rate, then absorber size is reduced, but amine volatility and viscosity may increase
Solution Approach 1:
The invention carefully controls the concentration parameters of the promoter amine within optimal ranges (0.1-20 wt%, preferably 0.5-10 wt%) to maximize mass transfer enhancement while minimizing volatility and viscosity increases. This parameter optimization ensures that the beneficial effects on kinetics are achieved without excessive amine loss.
Solution Approach 2:
The invention selects promoter amines with specific molecular characteristics (appropriate molecular weight, functional groups) that provide high mass transfer rates locally at the absorption interface while maintaining overall low volatility of the bulk solvent system. The promoter amine concentrates its effect where needed (at the gas-liquid interface) without compromising bulk stability.
3Loss of substance
If alcohol groups are added to reduce volatility, then amine loss is reduced, but solution viscosity increases due to hydrogen bonding
Solution Approach 1:
The invention optimizes the concentration of alcohol-containing promoter amine within specific ranges to achieve sufficient volatility reduction without excessive viscosity increase. By controlling the promoter amine concentration at 0.1-20 wt%, the system balances hydrogen bonding effects to minimize both amine loss and viscosity penalties.
Solution Approach 2:
The invention combines promoter amine with tertiary amine and water in a tri-component composite system where each component compensates for the drawbacks of others. The tertiary amine and water dilute the hydrogen bonding network formed by alcohol groups, thereby reducing viscosity while the promoter amine maintains low volatility through its molecular structure.
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
The solvent system achieves a significant increase in CO2 capture efficiency, reducing the size of absorber columns and operating costs, while maintaining low regeneration energy, making it suitable for both gas sweetening and post-combustion CO2 capture applications.
Implementation Method 1
The solvent includes a promoter amine and a tertiary amine... binding the acid gas in the fluid stream to the solvent to form an acid gas-solvent complex
Implementation Method 2
The liquid solution, CO2 rich amine solution, is then passed through a heat exchanger 14 to improve efficiency before being heated to a higher temperature in the stripper 12
Implementation Method 3
The stripper 12 removes the CO2 as a gas from the amine solution to produce a lean, or CO2 deficient solution
Data Source
AI summary
A solvent for removal of an acid gas from a fluid stream includes a promoter amine with a pKa of between 6.5 and 10.5 and a tertiary amine with a pKa of between 8.5 and 10.5.