Auto-refrigerated gas separation method for carbon dioxide capture and compression
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Solution Overview
Problem
Current methods for capturing carbon dioxide from mixed gas streams are inefficient and costly due to complexity, high energy requirements, and large equipment sizes, particularly in fossil fuel and industrial applications where carbon dioxide concentrations are lower.
Innovation Solution
A low-temperature gas separation process utilizing auto-refrigeration and gas recycling, involving multiple compression stages with inter-stage cooling and condensate removal, and recycling a portion of the gas back to the compressor, reducing overall energy demand and eliminating the need for external cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional compression and cooling systems are used for carbon dioxide capture, then carbon dioxide can be separated and liquefied, but the system requires large equipment sizes and high energy consumption
Solution Approach 1:
The compression process is divided into multiple stages with intercooling between stages. This segmentation allows for more efficient heat removal at intermediate pressures rather than attempting to cool the gas after final compression, reducing the total energy required for the compression and cooling process.
Solution Approach 2:
Cooling action is applied preliminarily between compression stages rather than after final compression. This preliminary cooling reduces the temperature and volume of the gas before subsequent compression stages, making the overall process more energy-efficient and reducing equipment size requirements.
2Manufacturing precision
If conventional compression and cooling systems are used for carbon dioxide capture, then carbon dioxide can be separated and liquefied, but the equipment size becomes large
Solution Approach 1:
The compression and cooling process is segmented into multiple stages with intercooling. This segmentation allows for compact heat exchanger design at each stage handling smaller temperature differentials, reducing the overall volume of cooling equipment required compared to a single-stage system.
Solution Approach 2:
Preliminary cooling between compression stages reduces the gas volume and temperature before subsequent processing steps. This preliminary action enables the use of smaller downstream equipment since the gas enters subsequent stages at lower temperatures and volumes.
3Device complexity
If simple single-stage compression is used, then the system is simpler, but carbon dioxide separation efficiency and purity are insufficient
Solution Approach 1:
The separation process is segmented into multiple compression stages with intercooling and condensate removal between stages. This segmentation allows for progressive purification, where each stage removes additional non-condensable gases, achieving high carbon dioxide purity (99% or higher) while maintaining manageable system complexity through modular design.
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 method achieves high carbon dioxide purity (up to 99%) with reduced energy consumption and costs, effectively handling carbon dioxide concentrations as low as 30% and efficiently operating within a compact system.
Implementation Method 1
passing the compressed gas stream through a first heat exchanger to form a first two-phase flow
Implementation Method 2
compressing the mixed gas stream in at least two compression stages
Implementation Method 3
compressing the mixed gas stream in at least two compression stages and subjecting the mixed gas stream to cooling and separating steps after each compression stage
Implementation Method 4
forming condensates that can be removed in condesate separator vessels
Implementation Method 5
passed through a drier, to further dry the gas stream
Implementation Method 6
In the liquefaction stage, the gas stream is further cooled for liquefying the carbon dioxide and separating it from non-condensable gases
Data Source
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AI summary
A system and method for capturing and separating carbon dioxide from mixed gas streams. The gas stream is processed in a structure including a compression module comprising a plurality of compressors, intercoolers and inter-stage condensate separators. The flow path from the compression module includes a plurality of flow separators, gas stream splitters, heat exchangers and at least a first mixer and a first expander. The gas stream is sequentially compressed and cooled to form process condensate and separate it from the compressed gas stream. The gas stream is further dried and cooled to liquefy carbon dioxide and separate it from the non-condensable portion. Selective expansion of liquid carbon dioxide streams provides cooling for the system, and further energy efficiency is achieved by selective recycling of portions of gas streams, allowing for compact equipment and economical operation, while providing for high purity product streams of carbon dioxide.