CO2 Absorbent Regeneration via Pressure Shift and Heat Recovery
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Solution Overview
Problem
Current CO2 capture processes are inefficient and costly due to the need for low-pressure regeneration of absorbents, which increases construction costs and energy consumption, and are not suitable for all absorbents, particularly amines, leading to reduced profitability of thermal power plants.
Innovation Solution
A method and plant design where the regenerator column operates at atmospheric pressure or higher, with steam generated at the base and gas compressed in multiple stages to recover heat, allowing for the use of medium temperature steam for other purposes and reducing reboiler duty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low pressure regeneration is used for carbonate absorbents, then CO2 stripping is effective, but construction cost increases dramatically and energy consumption increases
Solution Approach 1:
The invention changes the pressure parameter from sub-atmospheric (0.15 bar) to atmospheric or higher pressure operation in the regeneration column. This parameter change allows the use of conventional column sizes while maintaining effective CO2 stripping, thereby reducing construction costs and avoiding the need for voluminous columns.
Solution Approach 2:
The invention converts the harmful effect of high compression energy requirements into a beneficial outcome by using the compressed gas to generate steam for the reboiler. The compression process that would normally consume energy is instead used to produce the steam needed for regeneration, effectively converting an energy sink into an energy source.
2Reliability
If low pressure regeneration is used, then CO2 stripping is effective, but compression energy consumption increases significantly
Solution Approach 1:
The invention converts the harmful effect of high compression energy requirements into a beneficial outcome by using the compressed gas to generate steam for the reboiler. The compression process that would normally consume energy is instead used to produce the steam needed for regeneration, effectively converting an energy sink into an energy source.
Solution Approach 2:
The system uses its own compressed gas output to serve the steam generation requirement for the reboiler. The compression process self-serves the steam generation need, eliminating the requirement for external steam supply and reducing overall energy consumption.
3Adaptability or versatility
If low pressure regeneration is used, then carbonate absorbents can be stripped, but amine absorbents cannot be effectively regenerated
Solution Approach 1:
The invention changes the pressure parameter from sub-atmospheric to atmospheric or higher pressure operation. This parameter change is critical because amine absorbents require higher temperatures and pressures for effective CO2 stripping, and the new operating conditions enable amine regeneration while maintaining carbonate effectiveness.
Solution Approach 2:
The invention creates a universal regeneration system that can handle both carbonate and amine absorbents effectively. By operating at atmospheric or higher pressure with steam injection, the system achieves multi-functionality in regenerating different types of absorbents, making the process adaptable to various absorbent chemistries.
4Reliability
If atmospheric pressure or higher is used in regenerator, then amine absorbents can be regenerated effectively, but medium temperature heat energy demand increases
Solution Approach 1:
The invention converts the harmful effect of high heat energy demand into a beneficial outcome by using compressed gas to generate steam for the reboiler. The compression process that would normally consume energy is instead used to produce the steam needed for regeneration, effectively converting an energy sink into an energy source.
Solution Approach 2:
The system uses its own compressed gas output to serve the steam generation requirement for the reboiler. The compression process self-serves the steam generation need, eliminating the requirement for external steam supply and reducing overall energy consumption.
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 the demand for medium temperature heat energy, decreases energy costs, and enhances the overall efficiency of the CO2 capture process, making it more economically viable and reducing plant complexity.
Implementation Method 1
steam generated by heating lean absorbent at the base of the regenerator column, where gas, mainly comprising released CO2 and steam, is withdrawn from the top of the column
Implementation Method 2
the gas that is withdrawn from the top of the regenerator column is compressed and cooled by heat exchanging to recover the heat, before separation of the gas into CO2 and water
Implementation Method 3
water is introduced into the compressed gas between the compression stages
Data Source
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Figure 2
AI summary
A method and plant for regeneration of a rich absorbent having absorbed CO2, to give a regenerated, or lean absorbent, and CO2, where the rich absorbent is regenerated by stripping against steam in a regenerating column, where gas, mainly comprising released CO2 and steam, is withdrawn from the top of the column and separated to give a stream of CO2 that is removed, and condensed water that is recycled into the regenerator column, and where lean, or regenerated, absorbent is withdrawn from the base of the column, wherein the gas that is withdrawn from the top of the regenerator column is compressed and cooled by heat exchanging to recover the heat, before separation of the gas into CO2 and water.