Oxygen-Enriched Combined Cycle Combustion for Higher CO2 Flue Gas
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Solution Overview
Problem
Combined cycle power plants face inefficiencies in electricity generation due to the low CO2 concentration in flue gas, requiring substantial energy for capture and resulting in high costs and equipment requirements for carbon dioxide capture from natural gas combustion.
Innovation Solution
The method involves using a pressure swing adsorption process to separate air into a nitrogen-rich stream and an oxygen-rich stream, which is then used for oxygen-enriched combustion in combination with exhaust gas recycle to enhance the CO2 content of the flue gas, allowing for post-combustion capture with reduced energy consumption and equipment needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional air combustion is used in natural gas combined cycle plants, then the combustion process is simple and efficient, but the CO2 concentration in flue gas remains low (4.0-6.0 vol%), requiring substantial energy and equipment for capture
Solution Approach 1:
The patent changes the composition parameter of the combustion air by enriching it with oxygen (typically to 30-50 vol% O2). This parameter change directly increases the CO2 concentration in the flue gas from 4-6 vol% to 12-30 vol%, making CO2 capture more energy-efficient and economically viable.
Solution Approach 2:
The patent applies preliminary action by enriching the combustion air with oxygen before the combustion process occurs. This pre-enrichment modifies the combustion characteristics to produce a flue gas with higher CO2 concentration, thereby reducing the energy and equipment requirements for subsequent CO2 capture operations.
2Quantity of substance
If oxygen-enriched combustion is implemented to increase CO2 concentration in flue gas, then CO2 capture energy requirements are reduced, but additional equipment and capital costs are incurred for oxygen production and delivery
Solution Approach 1:
The patent utilizes parameter changes in the oxygen enrichment process, typically achieving 30-50 vol% O2 concentration in the combustion air. This optimized parameter range balances the need for high CO2 concentration in flue gas with the complexity and cost of oxygen production equipment.
Solution Approach 2:
The oxygen enrichment system serves multiple functions: it increases CO2 concentration in flue gas for easier capture, improves combustion efficiency, and can be integrated with various oxygen production methods (PSA, ASU, electrolysis), making the overall system more versatile and adaptable to different plant configurations.
3Quantity of substance
If air is separated using pressure swing adsorption to produce oxygen-rich stream for combustion, then CO2 concentration in flue gas is enhanced, but the process requires additional separation equipment and operational complexity
Solution Approach 1:
The patent applies parameter changes by utilizing pressure swing adsorption to produce oxygen-rich streams at various concentrations (typically 30-50 vol% O2). The pressure and composition parameters are optimized to balance oxygen production efficiency with the complexity of the separation equipment required.
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 increases the CO2 concentration in the flue gas to 12-30 vol%, reducing the volume of flue gas processed and the energy required for capture, while minimizing equipment costs and enabling the use of alternative capture technologies like membrane separation.
Implementation Method 1
separating air using a pressure swing adsorption process to form a nitrogen-containing stream containing 95 vol % or more of N2 and an oxygen-containing stream containing 25 vol % to 48 vol % of O2
Implementation Method 2
pressure swing adsorption process
Implementation Method 3
combusting a fuel with O2 from at least a portion of the oxygen-containing stream in the presence of a recycle stream in a combustion chamber of a turbine to form a flue gas
Implementation Method 4
combusting a fuel with O2
Data Source
AI summary
Systems and methods are provided for operating a combined cycle power plant while enhancing the CO2 content of the flue gas generated by the power plant. The CO2 content is enhanced by using a combination of exhaust gas recycle and oxygen-enriched combustion. The oxygen-containing flow for performing the oxygen-enriched combustion can be generated by an integrated pressure swing adsorption process that allows for production of a commercial grade nitrogen stream (95 vol % or more of N2) while also providing an oxygen-containing stream with an oxygen content between 25 vol % and 48 vol % with high 02 recovery.