Cryogenic CO2 Capture Through Phase Transition Separation
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Solution Overview
Problem
Current methods for capturing carbon dioxide from flue gases, such as oxy-combustion and amine scrubbing, are inefficient and costly, reducing the overall efficiency of power plants and requiring significant energy and capital expenditures.
Innovation Solution
A method and system that utilize cryogenic processes to compress and cool flue gases, separating carbon dioxide from nitrogen based on phase differences, allowing for energy recovery and reduced purification steps, resulting in a more efficient and cost-effective CO2 capture process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amine scrubbing is used to capture CO2 from flue gas, then CO2 separation efficiency is improved, but power plant efficiency deteriorates due to significant energy consumption
Solution Approach 1:
The patent utilizes phase transitions of CO2 by compressing flue gas to high pressure (e.g., 73-300 atm) and cooling it to temperatures where CO2 condenses into liquid or solid phase while nitrogen remains gaseous. This physical separation based on phase difference eliminates the need for energy-intensive chemical absorption processes like amine scrubbing, thereby maintaining power plant efficiency while achieving high CO2 separation efficiency.
Solution Approach 2:
The invention changes the physical parameters (pressure and temperature) of the flue gas to achieve CO2 separation. By compressing to high pressure and cooling to specific temperature ranges, CO2 undergoes phase change while nitrogen remains in gas phase, enabling efficient separation without the energy penalties associated with chemical absorption methods.
2Manufacturing precision
If oxy-combustion systems are used to increase CO2 concentration, then CO2 capture efficiency is improved, but capital costs increase due to air separation units
Solution Approach 1:
Instead of using oxy-combustion which requires expensive air separation units to produce high-concentration oxygen, this invention extracts and separates CO2 directly from conventional flue gas composition (4-14% CO2) by exploiting phase transitions at high pressure and low temperature. This approach achieves effective CO2 capture without the need for costly air separation infrastructure.
3Manufacturing precision
If conventional CO2 capture methods are used, then CO2 separation is achieved, but purification costs increase due to required distillation steps
Solution Approach 1:
The patent achieves direct purification of CO2 through phase transitions. By compressing to high pressure and cooling to temperatures below CO2's condensation point, pure CO2 condenses into liquid or solid phase while impurities like nitrogen remain gaseous. The condensed CO2 can be directly collected and stored without requiring additional distillation or purification steps, significantly reducing purification costs.
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 process achieves high CO2 separation efficiency with reduced energy and capital costs by forming a solid-phase CO2 that does not require distillation, enabling energy storage and improved operational efficiency.
Implementation Method 1
The methods and systems use cryogenics to compress and cool the carbon dioxide to yield condensed carbon dioxide from the flue gas stream
Implementation Method 2
reducing the temperature of the compressed gas stream to a second temperature T2 using a second heat exchanger or using a second heat exchanger in combination with expansion of the compressed gas stream, wherein T2<T1 and wherein at least a portion of the carbon dioxide from the compressed gas stream condenses
Implementation Method 3
reducing the temperature of the compressed gas stream to a temperature T1 using a first heat exchanger; reducing the temperature of the compressed gas stream to a second temperature T2 using a second heat exchanger
Implementation Method 4
reducing the temperature of the compressed gas stream to a second temperature T2 using a second heat exchanger in combination with expansion of the compressed gas stream
Data Source
AI summary
A method for capturing carbon dioxide from a flue gas includes (i) removing moisture from a flue gas to yield a dried flue gas; (ii) compressing the dried flue gas to yield a compressed gas stream; (iii) reducing the temperature of the compressed gas stream to a temperature T1 using a first heat exchanger; (iv) reducing the temperature of the compressed gas stream to a second temperarature T2 using a second heat exchanger stream, where T2<T1 and at least a portion of the carbon dioxide from the compressed gas stream condenses, thereby yielding a solid or liquid condensed-phase carbon dioxide component and a light-gas component; (v) separating purities the condensed-phase component from the light-gas component to produce a condensed-phase stream and a light-gas stream; and (vi) using at least a portion of the condensed-phase stream and/or the light-gas stream in the second heat exchanger.