Two-Stage Flash Solvent Regeneration for CO2 Capture
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Solution Overview
Problem
Current processes for removing carbon dioxide from carbon dioxide-loaded solvents are energy-intensive and costly due to high energy consumption in compression and liquefaction steps, particularly in the context of capturing CO2 from fossil fuel power plants to mitigate climate change.
Innovation Solution
A two-stage flash process where the carbon dioxide-loaded solvent is heated and pressurized, then flashed in a first stage to reduce CO2 content, and subsequently treated in a second stage at lower temperatures and pressures to further reduce CO2 content, followed by multi-stage compression to high pressure for efficient solvent regeneration and CO2 recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional single-stage desorption with steam heating is used, then CO2 can be removed from the solvent, but high energy consumption is required for heating and subsequent compression
Solution Approach 1:
The desorption process is divided into two stages: a first stage at high temperature and high pressure that removes the majority of CO2, and a second stage at lower temperature and pressure that completes the regeneration. This segmentation allows each stage to operate under optimized conditions, reducing the total energy input required compared to single-stage desorption followed by high-pressure compression
Solution Approach 2:
The process utilizes changes in temperature and pressure parameters between two stages to optimize CO2 removal. The first stage operates at elevated temperature and pressure to achieve bulk CO2 stripping, then the second stage operates at reduced parameters to complete regeneration, avoiding the need for high-pressure compression of CO2
2Reliability
If high pressure compression is applied to CO2 from the desorber, then CO2 can be stored or transported, but the compression cost and energy consumption increase significantly
Solution Approach 1:
The process performs preliminary CO2 removal and concentration during the two-stage flash desorption before compression is needed. By removing CO2 at controlled stages and maintaining it in a concentrated gaseous form, the subsequent compression requires less energy compared to compressing CO2 from atmospheric pressure after conventional single-stage desorption
3Productivity
If auxiliary steam is used to vaporize amine solution in a reboiler, then CO2 can be stripped from the solvent, but additional energy input is required
Solution Approach 1:
The process extracts and removes the majority of CO2 from the solvent in the first flash stage before the solvent enters the reboiler. This pre-removal reduces the CO2 partial pressure in the reboiler, allowing desorption to proceed more efficiently with less auxiliary steam energy input, as the reboiler only needs to handle the remaining CO2 removal
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 process significantly reduces energy and cost requirements by achieving substantial CO2 content reduction in solvents and efficient compression, compared to conventional methods, while enabling effective solvent regeneration and high-pressure CO2 recovery.
Implementation Method 1
heating the carbon dioxide-loaded solvent to a first temperature and applying a first pressure to the carbon dioxide-loaded solvent
Implementation Method 2
flashing carbon dioxide from the carbon dioxide-loaded solvent in the first stage flash apparatus
Implementation Method 3
feeding the first treated solvent to a second stage flash apparatus at a second temperature that is lower than the first temperature and a second pressure that is lower than the first pressure
Implementation Method 4
a second pressure that is lower than the first pressure
Implementation Method 5
flashing carbon dioxide from the first treated solvent in the second stage flash apparatus
Data Source
Figure 1~2
AI summary
A process for removing carbon dioxide from a carbon dioxide-loaded solvent uses two singes of Hash apparatus. Carbon dioxide is flashed from the solvent at a higher temperature and pressure in the 'first stage, and a lower temperature and pressure in the second stage, and is fed to a. multi-stage compression train for high pressure liquefaction. Because some of the carbon dioxide fed to the compression train is already under pressure, less energy is required, to further compress the carbon, dioxide to a liquid state, compared, to conventional processes.