Cryogenic CO2 Separation Heat Integration With Step-Wise Cooling
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Solution Overview
Problem
Existing CO2 capture systems from flue gas are costly due to the use of external refrigerants and are prone to fouling from trace components in flue gas, requiring extensive pre-treatment and expensive heat exchanger materials like aluminum.
Innovation Solution
A CO2 separation system using a refrigeration circuit with a multistage compressor, condensers, and a stripper column, employing propane or propylene as refrigerants, and an adsorption drier to remove water vapor, optimizing energy consumption through step-wise cooling and minimizing the need for pre-treatment equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If external refrigerants are used for CO2 condensation, then condensation efficiency is improved, but investment costs and operational costs increase
Solution Approach 1:
The system uses the CO2-rich flue gas itself as the refrigerant medium. The flue gas is compressed, cooled, and expanded to achieve auto-refrigeration, eliminating the need for external refrigerants. This self-service approach reduces both investment costs for refrigeration equipment and operational costs for refrigerant purchase and handling, while maintaining effective CO2 condensation capability
Solution Approach 2:
The CO2-rich flue gas serves multiple functions: it is the process gas to be treated, the working fluid for compression and expansion, and the refrigerant medium for CO2 condensation. This multi-functionality eliminates the need for separate external refrigerant systems, reducing overall system complexity and cost
2Productivity
If aluminum heat exchangers are used for CO2 condensation, then heat exchange efficiency is improved, but sensitivity to fouling by trace components increases
Solution Approach 1:
The system implements preliminary cleaning actions before CO2 condensation by removing dust, sulfur compounds, metals, nitrogen oxides, and other trace components through gas cleaning operations. This pre-treatment prevents fouling of subsequent heat exchangers, allowing the use of more robust and less fouling-sensitive heat exchanger designs
Solution Approach 2:
The system employs robust, easily replaceable heat exchanger designs that are less sensitive to fouling. Rather than using expensive aluminum heat exchangers that are highly efficient but fouling-sensitive, the system uses more durable materials that can withstand trace component exposure without requiring frequent replacement or maintenance
3Reliability
If extensive pre-treatment equipment is installed, then protection against fouling is improved, but device complexity increases
Solution Approach 1:
The system combines multiple gas cleaning functions into an integrated pre-treatment train that removes dust, sulfur compounds, metals, and nitrogen oxides in a coordinated sequence. By merging these functions and optimizing their arrangement, the system achieves comprehensive protection against fouling while minimizing the overall complexity compared to separate, standalone treatment units
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 system achieves cost-effective and efficient CO2 separation with robust, fouling-resistant designs, reducing the need for pre-treatment and allowing for simpler equipment and materials, lowering energy consumption and operational costs.
Implementation Method 1
cooling, or compression and cooling, of the flue gas to condense CO2 in liquid or solid form
Implementation Method 2
the CO2 rich flue gas is compressed, cooled and expanded to achieve condensation of the CO2
Implementation Method 3
at least one flue gas adsorption drier
Data Source
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AI summary
The present invention relates to a flue gas treatment system for removing CO2 from a flue gas stream (255) wherein the system comprises a flue gas compressor (244), at least one flue gas adsorption drier (262), a refrigeration system (252,280,270,264,260) and a stripper column (271) allowing distillation. Also a method for condensation of carbon dioxide (CO2) in a flue gas stream comprising a step of separation by distillation of the condensed CO2 is provided by the invention.