Biocatalyst CO2 Stripping Without Reboiler Bubble Damage
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Solution Overview
Problem
Existing biocatalyst-based CO2 capture processes face challenges with enzyme stability due to exposure to high pH and temperature conditions, particularly from bubble formation and new gas-liquid interfaces created during boiling, which leads to rapid biocatalyst degradation.
Innovation Solution
Implementing process designs that minimize exposure to bubble-formation conditions by using a falling-film evaporator to generate stripping gas, an external stripping gas loop, or non-condensable gases, thereby reducing the generation of new gas-liquid interfaces and enhancing biocatalyst lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the absorption solution is heated to high temperatures (50-90°C) in a reboiler to generate steam for stripping, then the CO2 desorption efficiency is improved, but the biocatalyst stability deteriorates due to bubble formation and new gas-liquid interfaces
Solution Approach 1:
The harmful reboiler unit that generates bubbles and new gas-liquid interfaces is completely removed from the system. Instead of heating the biocatalyst-containing solution in a reboiler, the patent uses an external steam generator that produces steam separately, then introduces it to the stripping column where CO2 desorption occurs without direct contact between the biocatalyst and bubble-formation conditions.
Solution Approach 2:
An external steam generator acts as an intermediary device that produces the stripping steam separately from the biocatalyst-containing absorption solution. The steam is generated in a dedicated unit and then introduced to the stripping column, serving as the medium for CO2 removal without requiring the biocatalyst to be exposed to high-temperature boiling conditions.
2Productivity
If the enzyme is exposed to alkaline pH higher than 9 and temperatures ranging from 10-90°C during CO2 capture and stripping, then the CO2 capture performance is improved, but the enzyme lifetime deteriorates
Solution Approach 1:
The CO2 capture process is segmented into distinct functional units: an absorption column where CO2 is captured at mild conditions, a stripping column where CO2 is removed using externally generated steam, and a separate steam generator. This segmentation allows the biocatalyst to operate only in the absorption unit under favorable conditions, while the harsh stripping conditions are handled in a separate unit without direct contact with the enzyme.
Solution Approach 2:
The absorption solution acts as an intermediary carrier that transports CO2 from the absorption column to the stripping column. The biocatalyst remains in the absorption solution during CO2 uptake, then the CO2-loaded solution is transferred to the stripping column where externally generated steam performs the desorption, minimizing the biocatalyst's exposure to detrimental conditions.
3Ease of operation
If a reboiler is used to generate stripping steam by boiling the absorption solution, then the stripping gas supply is improved, but the biocatalyst degradation accelerates due to extensive bubble formation
Solution Approach 1:
The reboiler unit that causes biocatalyst degradation through bubble formation is extracted and replaced with an external steam generator. The steam generation function is separated from the biocatalyst-containing solution, eliminating the harmful bubble-formation step while maintaining the necessary steam supply for stripping operations.
Solution Approach 2:
The system uses a portion of the CO2-lean absorption solution itself as the feedstock for steam generation in the external steam generator. This self-service approach allows the process to generate its own stripping steam from its own circulation stream without requiring external fuel or additional water resources.
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 proposed methods significantly increase biocatalyst stability and longevity by minimizing exposure to detrimental conditions, leading to improved CO2 capture efficiency and reduced biocatalyst costs.
Implementation Method 1
using a falling-film evaporator to generate stripping gas
Implementation Method 2
the absorption solution is heated up to temperature ranging from 50 to 90° C.
Implementation Method 3
the enzyme carbonic anhydrase to increase the CO2 capture performance of absorption solutions
Implementation Method 4
contacting a biocatalyst-containing CO2-rich absorption solution with a stripping gas in a stripping system to create a driving force which desorbs CO2 from the biocatalyst-containing CO2-rich absorption solution
Implementation Method 5
The gas (19) leaving the stripping unit (9) is fed to a condenser (14) where the steam is condensed
Data Source
AI summary
A method for stripping CO2 from a biocatalyst-containing CO2-rich absorption solution to produce a biocatalyst-containing CO2-lean absorption solution and a CO2-rich gas is provided. The method includes generating a stripping gas from a portion of the biocatalyst-containing CO2-lean absorption solution in a stripping gas generation unit, and contacting the biocatalyst-containing CO2-rich absorption solution with the stripping gas in a gas-liquid contactor to produce the CO2-lean absorption solution and the CO2-rich gas.