Recuperated Micro Gas Turbine Combustor with Segmented Single Burner
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Solution Overview
Problem
Recuperated micro gas turbines face challenges in maintaining low combustor pressure loss, achieving complete combustion with low emissions of CO, UHC, and NOx across various operating conditions, including base load, part load, and transient states, while ensuring reliable light-off and low cost.
Innovation Solution
The combustor design optimizes the relative position of the fuel injector and flame stabilization device to stage combustion and mixing, ensuring NOx levels remain below single-digit ppm, with a flame stabilization device comprising concentric cylindrical rings and vanes that maintain pressure loss under 1.5%, allowing for stable and complete combustion without additional burner assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple burners are used to ensure stable combustion at all operating conditions, then combustion stability is improved, but device complexity and cost increase
Solution Approach 1:
The single burner is segmented into distinct functional zones: a fuel-injection zone for primary combustion and a mixing zone for combining burned gases with compressed air. This segmentation allows one burner to perform multiple functions that traditionally required multiple burners, achieving stable combustion across all operating conditions while simplifying the overall burner configuration.
Solution Approach 2:
The single burner is designed to be multi-functional, serving as both the primary combustion device and the mixing device. By integrating the fuel injector and flame stabilization device within the same burner assembly, the system achieves reliable light-off, stable combustion, and emission control without requiring separate pilot burners or multiple main burners.
2Reliability
If fuel-air mixing is enhanced to ensure complete combustion, then combustion completeness is improved, but NOx formation increases due to higher temperatures and longer residence time
Solution Approach 1:
The combustion process is segmented into two distinct stages within the single burner: first, complete combustion of fuel in the fuel-injection zone; second, mixing of the burned gases with compressed air in the mixing zone. This segmentation allows complete combustion to occur while the subsequent mixing with cool compressed air prevents excessive temperature rise and limits NOx formation.
Solution Approach 2:
Compressed air is introduced into the mixing zone before the exhaust gases leave the combustor. This preliminary mixing action ensures that the hot burned gases are rapidly cooled, maintaining temperatures below the threshold for significant NOx formation while still achieving complete combustion in the initial fuel-injection zone.
3Temperature
If compressed air is used for cooling the flame tube, then flame tube cooling is improved, but combustor pressure loss increases
Solution Approach 1:
The compressed air that would traditionally be used solely for cooling the flame tube is instead utilized dual-purpose: it cools the flame tube while simultaneously serving as the mixing medium in the mixing zone. This eliminates the need for separate cooling air flows and reduces overall combustor pressure loss.
Data Source
Figure 1~2
Figure 3~5
AI summary
According to the invention, a recuperated micro gas turbine combustor has a casing (23), liner (27), fuel injector (33) and a flame stabilization device (29). This flame stabilization device is characterized by a swirl strength and air passage geometry as such that the pressure loss over the device is less than 1,5%. The flame stabilization device and the fuel injector form together with the liner inlet/head hardware a single burner. The position of the fuel injector with respect to the flame stabilization device is optimized for limited fuel mixing with only part of the air through the flame stabilization device. The burner first stages combustion of the mixed fuel and then mixing with the remaining air. Particularly, combustion is complete and mixing occurs as such that NOx can never increase above single-digit ppm.