Cryogenic Flue Gas Compression and Cooling for CO2 Capture Efficiency
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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, requiring significant energy and capital expenditures, and often decrease the overall efficiency of power plants.
Innovation Solution
A method using cryogenic processes to compress and cool flue gases, separating carbon dioxide from nitrogen and other light gases based on phase differences, allowing for energy recovery and reduced purification steps, and incorporating high-pressure energy storage to enhance efficiency and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amine scrubbing is used to capture CO2 from flue gas, then CO2 capture efficiency is improved, but power plant efficiency deteriorates
Solution Approach 1:
The patent applies phase transitions by cooling flue gas to condense CO2 from its gaseous state into liquid or solid form, enabling separation from nitrogen and other light gases. This cryogenic condensation approach achieves high CO2 capture efficiency without the energy-intensive chemical absorption processes used in amine scrubbing, thereby preserving power plant efficiency.
Solution Approach 2:
The invention changes the temperature parameter of the flue gas from ambient conditions to cryogenic temperatures (below -78.5°C), fundamentally altering the physical state and separation behavior of CO2. This parameter change enables efficient CO2 capture through condensation rather than chemical absorption, reducing the energy penalty on power plant operation.
2Measurement precision
If oxy-combustion is used to increase CO2 concentration, then CO2 capture efficiency is improved, but capital costs deteriorate
Solution Approach 1:
The patent extracts CO2 from flue gas through cryogenic condensation without requiring the complex oxy-combustion system with air separation units. By directly cooling the flue gas to condense CO2, the invention eliminates the need for expensive oxygen production equipment while achieving effective CO2 separation and concentration.
3Use of energy by moving object
If cryogenic cooling is applied to separate CO2, then energy efficiency is improved, but device complexity deteriorates
Solution Approach 1:
The patent merges the CO2 separation function with the existing flue gas cooling requirement. By utilizing the necessary cooling process to achieve both temperature reduction and CO2 condensation simultaneously, the invention avoids adding separate complex purification systems, thereby managing device complexity while maintaining energy efficiency.
4Reliability
If CO2 is compressed in gaseous phase for storage, then storage readiness is improved, but energy consumption deteriorates
Solution Approach 1:
The patent utilizes phase transition by condensing CO2 into liquid or solid form during the separation process. This condensed CO2 is then compressed with significantly lower energy consumption compared to compressing gaseous CO2, while still achieving the required storage conditions. The phase change occurs naturally during cryogenic separation, eliminating the need for high-energy gas compression.
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 achieves high carbon dioxide capture efficiency (>95%) with reduced energy and capital costs, enabling more economical CO2 capture and storage by forming a solid CO2 phase that avoids costly distillation and compression, and utilizing stored energy to manage peak demand.
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
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 3
The methods and systems are made economical in part by using the cooled separated light gases (e.g., nitrogen) to cool the flue gases. In this manner a portion of the energy needed to cool the flue gas is recovered
Data Source
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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 temperature 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 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.