Cryogenic CO2 Condensation Using Self-Refrigerated Flue Gas
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Solution Overview
Problem
Existing CO2 capture systems from flue gas are costly and prone to fouling due to the use of external refrigerants and sensitive materials like aluminum, requiring extensive gas cleaning processes.
Innovation Solution
A refrigeration system with a multistage refrigerant compressor and heat exchanger design that integrates CO2 condensation using a refrigerant circuit with high heat integration, minimizing vapor fraction and utilizing CO2 as a cooling medium to achieve efficient CO2 separation with robust and cost-effective heat exchanger designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If external refrigerant is used for CO2 condensation, then CO2 separation efficiency is improved, but system cost and operational expense 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 condensation of CO2, eliminating the need for external refrigerants. The liquid CO2 product serves as the cooling medium for the flue gas, creating a self-sufficient refrigeration cycle that reduces system cost and complexity.
2Productivity
If brazed aluminum heat exchangers are used for CO2 condensation, then condensation efficiency is improved, but sensitivity to fouling by trace components increases
Solution Approach 1:
The invention changes the material parameter of the heat exchanger from sensitive brazed aluminum to robust materials like stainless steel or titanium that are resistant to fouling by mercury, particulate matter, and other trace components in flue gas. This allows the system to operate without extensive upstream gas cleaning equipment.
3Reliability
If extensive gas cleaning is implemented upstream of CO2 condensation, then heat exchanger reliability is improved, but system complexity and investment cost increase
Solution Approach 1:
The invention uses robust, fouling-resistant heat exchanger materials that can tolerate the presence of trace contaminants without requiring extensive cleaning equipment. This approach accepts the presence of harmful components rather than attempting to remove them, simplifying the overall system by eliminating particle filters, mercury adsorbers, and SOX/NOX scrubbers.
4Use of energy by moving object
If tight temperature approaches are used in autorefrigeration systems, then energy efficiency is improved, but requirement for extensive gas cleaning increases
Solution Approach 1:
The invention uses robust heat exchanger materials that are insensitive to fouling, allowing the system to maintain tight temperature approaches for energy efficiency without requiring extensive gas cleaning. The material parameter change enables the system to tolerate trace components while achieving efficient heat transfer.
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 high CO2 yields of over 90% with reduced energy consumption and eliminates the need for extensive gas cleaning, using simple and robust heat exchanger designs that are resistant to fouling.
Implementation Method 1
Cooling of the flue gas to its condensation temperature may be achieved by various means, e.g. using a suitable external refrigerant. CO2 capture systems using an external refrigerant can be expensive, both in terms of investment costs and in terms of operational costs.
Implementation Method 2
A refrigeration system with a multistage refrigerant compressor and heat exchanger design that integrates CO2 condensation using a refrigerant circuit with high heat integration
Implementation Method 3
a multistage refrigerant compressor, configured to compress the refrigerant from the flue gas chiller, first CO2 condenser and second CO2 condenser
Implementation Method 4
a refrigerant condenser, a refrigerant chiller, a flue gas chiller, a first CO2 condenser, a second CO2 condenser
Data Source
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AI summary
A refrigeration system for condensation of carbon dioxide (CO2) in a flue gas stream (55), said system comprising a refrigeration circuit (50), a flue gas treatment system comprising a flue gas compressor (44) and a refrigeration system for condensation of CO2 (66,72), and a method for condensation of CO2 in a flue gas stream using a circulating stream of an external refrigerant.