Stoichiometric Exhaust Gas Recirculation for Power Plants
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Solution Overview
Problem
Gas turbine power plants face challenges in reducing emissions and managing excess oxygen in exhaust streams, which hinders the effectiveness of emissions reduction and carbon capture processes.
Innovation Solution
The implementation of a Stoichiometric Exhaust Gas Recirculation (SEGR) system that recirculates low oxygen content gas back into the combustion process, allowing for stoichiometric combustion and reducing oxygen content in the exhaust, thereby enabling the use of NOx reduction catalysts and enhancing carbon capture capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If excess air is used within the combustion process to control turbine temperatures and manage emissions, then turbine temperature control is improved, but exhaust stream oxygen content increases
Solution Approach 1:
A recirculation system acts as an intermediary to capture exhaust gases and redirect them back to the combustion chamber inlet, creating a closed-loop flow path that enables precise control of combustion conditions without excess air
Solution Approach 2:
The system changes the combustion parameter from excess air operation to stoichiometric combustion by controlling the recirculation ratio, transforming the combustion process to achieve complete fuel consumption while maintaining temperature control
2Object-generated harmful factors
If stoichiometric combustion is implemented to reduce exhaust oxygen, then emissions reduction capability is improved, but combustion temperature control becomes more difficult
Solution Approach 1:
The recirculation system provides feedback by continuously returning exhaust gases to the combustion chamber, allowing the system to self-regulate combustion temperature and maintain stoichiometric conditions without external intervention
Solution Approach 2:
The recirculated exhaust gas serves multiple functions simultaneously: it acts as a diluent to control temperature, provides a oxygen source for stoichiometric combustion, and serves as a carrier for emissions reduction catalysts
3Object-generated harmful factors
If a recirculation loop is added to enable stoichiometric combustion, then emissions reduction is improved, but device complexity increases
Solution Approach 1:
The recirculation system merges the exhaust gas flow with the fresh air flow at the combustion chamber inlet, combining multiple flow streams into a single unified combustion process that achieves emissions reduction without requiring separate treatment systems
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 results in a nearly oxygen-free exhaust stream, facilitating emissions reductions and enabling more efficient carbon capture, while also improving the operational safety of gas turbine engines by managing high combustion temperatures.
Implementation Method 1
at least one main air compressor for compressing ambient air into a compressed ambient gas flow
Implementation Method 2
for mixing at least a first portion of the compressed ambient gas flow with at least a first portion of a recirculated low oxygen content gas flow and a fuel stream to form a combustible mixture and for burning the combustible mixture
Implementation Method 3
a turbine connected to the turbine combustor and to a turbine shaft. The turbine is arranged to be driven by the recirculated low oxygen content gas flow from the turbine combustor
Data Source
AI summary
A power plant arrangement and method of operation are provided. The power plant arrangement comprises at lease one main air compressor and one or more gas turbine assemblies. Each assembly comprises a turbine combustor for mixing a portion of a compressed ambient gas flow with a portion of a recirculated low oxygen content gas flow and a fuel stream, and burning the combustible mixture to form the recirculated low oxygen content flow. The assembly further comprises a turbine compressor, fluidly connected to the turbine combustor, and connected to a turbine shaft that is arranged to be driven by rotation of a turbine. The assembly also comprises a recirculation loop for recirculating at least a portion of the recirculated low oxygen content gas flow from the turbine to the turbine compressor.