CO2 Absorber Mist Control via Temperature Management
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Solution Overview
Problem
Amine-based CO2 absorbers experience high emissions of amines and their degradation products in the form of mist, which are difficult to remove using conventional demisters and wet electrostatic precipitators due to the small droplet size and high operating costs of these methods.
Innovation Solution
The solution involves controlling the temperature of the CO2 absorbing solvent to be equal to or higher than the maximum temperature in the absorption section, avoiding rapid cooling and mist formation, and using multiple downstream washing steps with water at or above the wet bulb temperature to prevent mist formation, along with an optional acid wash to remove alkaline compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the gas is rapidly cooled in the absorption section to condense water and remove amine vapour, then amine emission to air is reduced, but mist containing amines and degradation products is formed and released
Solution Approach 1:
The absorber is divided into distinct functional sections: a CO2 absorption section and separate water wash sections. The water wash sections are positioned above the absorption section to handle mist removal, while the absorption section focuses on CO2 capture. This segmentation allows each section to optimize its function without interfering with the other.
Solution Approach 2:
A water wash section acts as an intermediary between the CO2 absorption section and the atmosphere. This intermediate stage washes the gas stream with water to remove mist containing amines and degradation products before the gas is released, thereby reducing harmful emissions without requiring rapid cooling in the absorption section.
2Object-generated harmful factors
If conventional demisters are used to remove mist, then amine emission is reduced, but the small droplet size makes removal difficult and inefficient
Solution Approach 1:
The invention changes the approach from mechanical mist separation to thermal parameter control. By maintaining higher temperatures in the absorption section and controlling the temperature profile, the system prevents mist formation at the source rather than attempting to separate fine droplets mechanically. This parameter change makes the solution more reliable for removing ultrafine mist particles.
3Object-generated harmful factors
If wet electrostatic precipitators are used to remove mist, then amine emission is reduced, but operating costs increase significantly
Solution Approach 1:
The water wash sections utilize the existing gas flow and gravitational forces to achieve mist removal without requiring external energy input for mechanical separation devices. The system uses the natural upward flow of gas and the counter-current water flow to remove mist, making the process self-service and eliminating the need for energy-intensive electrostatic precipitators.
Solution Approach 2:
The invention replaces expensive, energy-intensive electrostatic precipitators with simple water wash sections that use readily available water and minimal energy. The water wash sections provide effective mist removal at a fraction of the operating cost of electrostatic precipitators, using inexpensive water instead of expensive electrical energy.
4Object-generated harmful factors
If low temperature water wash is used to minimize amine vapour pressure, then amine slip to atmosphere is reduced, but mist formation increases
Solution Approach 1:
The water wash sections are positioned above the absorption section to perform preliminary mist removal before the gas reaches the atmosphere. By placing the water wash sections in this preliminary position, mist is removed early in the process when it first forms, preventing further accumulation and release of amine-containing mist to the atmosphere.
Solution Approach 2:
The invention adds a vertical dimension to the absorber design by stacking water wash sections above the absorption section. This dimensional arrangement allows the water wash to occur in a separate spatial zone, enabling temperature optimization in each section independently - higher temperature in the absorption section to prevent mist formation, and water wash above to remove any mist that does form.
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 the formation and release of amine-containing mist, achieving high removal efficiency of amines and degradation products while maintaining CO2 capture performance and water balance.
Implementation Method 1
CO2 is captured from the gas by causing the gas to flow counter current to a CO2 absorbing solvent introduced into a CO2 absorption section in an absorber so that CO2 present in the gas is absorbed by the CO2 absorbing solvent
Implementation Method 2
The main objective of the water wash is to absorb amine vapour in order to minimise emission of amine to air. Another objective is to cool the gas and condense water
Implementation Method 3
The water wash sections are operated at a temperature that is equal to or higher than the wet bulb temperature of the gas entering the washing section, to avoid cooling the gas below the wet bulb temperature and thereby avoid mist formation
Data Source
AI summary
A method for capturing CO2 from a CO2 containing gas (1), such as en exhaust gas from a thermal power plant fired on carbonaceous fuel, or any other CO2 containing industrial gas, where CO2 is captured from the gas by causing the gas to flow counter current to a CO2 absorbing solvent introduced into a CO2 absorption section (3) in an absorber (2) so that CO2 present in the gas is absorbed by the CO2 absorbing solvent to form a CO2 rich solvent (5), where CO2 rich solvent is collected on the bottom of the of the absorption column and withdrawn for regeneration, and where the treated exhaust gas (8) is released to the atmosphere after being subjected to one or more washing step(s) (6,7), wherein the temperature of the CO2 absorbing solvent (4) introduced into the CO2 absorption section has a temperature that is less than 5° C. lower than the maximum temperature in the absorption section of the absorber, is described.