Gas Turbine Compressor Inlet Segmentation for Low Oxygen Combustion
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Solution Overview
Problem
Conventional gas turbine power plants with exhaust gas recirculation face challenges in minimizing residual oxygen content, leading to incomplete combustion and increased NOx emissions due to the mixing of oxygen-rich cooling air with recirculated exhaust gases.
Innovation Solution
A gas turbine power plant design with an open cooling system using low-oxygen gas and a divided compressor inlet to separate fresh air and recirculated exhaust gas streams, minimizing their mixing through concentric sectors and centrifugal separation, and employing compressor blades with separating band segments to enhance stratification and reduce oxygen-rich air introduction into the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If exhaust gas recirculation is used to reduce NOx emissions and increase CO2 partial pressure, then emissions control and efficiency are improved, but the residual oxygen content in exhaust gases remains high due to mixing with oxygen-rich cooling air
Solution Approach 1:
The compressor inlet is divided into separate sectors: one for fresh air intake and another for recirculated exhaust gas intake. This segmentation prevents mixing of the two streams at the inlet, allowing independent control and maintaining low oxygen content in the recirculated stream.
Solution Approach 2:
The oxygen-rich cooling air is extracted and separated from the recirculated exhaust gas stream. By taking out the cooling air function and providing it separately, the recirculated exhaust gas maintains its low oxygen composition without contamination from cooling air mixing.
2Reliability
If fresh air is mixed with recirculated exhaust gases to ensure good combustion, then combustion reliability is improved, but the oxygen content in recirculated exhaust gases increases
Solution Approach 1:
Different regions of the compressor inlet are assigned different functions: the fresh air sector provides oxygen for combustion, while the recirculated exhaust gas sector maintains low oxygen content. This local differentiation allows both combustion reliability and low residual oxygen to be achieved simultaneously.
Solution Approach 2:
The divided compressor inlet sectors act as an intermediary structure that prevents direct mixing between fresh air and recirculated exhaust gases. This intermediary arrangement allows both streams to be delivered to the combustion chamber without contaminating each other, maintaining the desired oxygen levels.
3Temperature
If cooling air is routed past the combustion chamber through the cooling air system, then cooling of hot gas parts is achieved, but oxygen contained in cooling air cannot be used for incineration and residual oxygen remains high
Solution Approach 1:
The cooling air function is extracted and separated from the recirculated exhaust gas stream. By providing cooling air separately through the cooling air system rather than mixing it with recirculated gases, the oxygen in cooling air does not contaminate the recirculated stream, maintaining low residual oxygen content.
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 design effectively minimizes residual oxygen in the exhaust gases, ensuring complete combustion and reducing NOx emissions by maintaining a higher oxygen content in the combustion chamber, thereby improving operational reliability and efficiency.
Implementation Method 1
a gas which has an oxygen concentration that is less than the average oxygen concentration of the compressor intake flow is referred to as a gas low in oxygen
Implementation Method 2
a feed for fresh air leading through a first sector of the compressor inlet and a feed for the first exhaust gas stream leading through a second sector of the compressor inlet
Data Source
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AI summary
A gas turbine power plant with exhaust gas recirculation is described, featuring a split compressor inlet for the separate supply of recirculated exhaust gas and fresh air to the compressor inlet, as well as compressor blades with a separating rib that inhibits the mixing of recirculated exhaust gas and fresh air during compression.