Multi-tube Nozzle Injection System for Turbomachine Combustion
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Solution Overview
Problem
Gas turbine engines face a challenge in achieving efficient combustion while minimizing nitrogen oxide (NOx) emissions, as higher gas stream temperatures increase efficiency but also produce higher NOx levels, and pure H2 combustion often results in flashback conditions due to insufficient fuel and air mixing.
Innovation Solution
The design of a turbomachine with a multi-tube nozzle injection system where fuel is distributed through a plenum to multiple tube elements extending radially, creating a mixing region that enhances fuel and air mixing, stabilizes the flame, and reduces flashback by cooling the circumferential wall and tube elements, thereby lowering temperatures and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher gas stream temperatures are used to increase combustion efficiency, then energy conversion efficiency is improved, but nitrogen oxide emissions increase
Solution Approach 1:
The injection nozzle is divided into multiple tube elements (at least three) arranged radially, with each tube receiving fuel through a plenum. This segmentation creates multiple separate mixing and combustion zones, improving overall combustion efficiency while distributing heat generation to reduce localized temperatures that produce NOx
Solution Approach 2:
Different regions of the combustion chamber receive different fuel-air mixture characteristics through the radially arranged tube elements. The circumferential wall cooling and selective fuel distribution create local quality variations that optimize combustion in different zones while controlling emission formation
2Productivity
If pure H2 or high H2 combustion is used to increase efficiency, then energy efficiency is improved, but flashback conditions occur due to insufficient fuel and air mixing
Solution Approach 1:
Fuel is introduced into a plenum chamber before reaching the tube elements, allowing preliminary mixing with air to occur upstream. This preliminary action ensures proper fuel-air mixing is achieved before combustion, preventing flashback conditions while maintaining high H2 combustion efficiency
Solution Approach 2:
The plenum chamber acts as an intermediary zone between fuel injection and combustion tube elements. This intermediate space allows fuel and air to mix thoroughly before entering the combustion region, mediating the interaction between fuel delivery and combustion to prevent unstable combustion and flashback
3Stability of the object's composition
If fuel jet penetration is increased to improve mixing, then fuel-air mixing is improved, but fuel flows through the boundary layer in the premixer tube causing flashback
Solution Approach 1:
Instead of a single large fuel jet, the system uses multiple smaller tube elements radially arranged around the central axis. Each tube provides a separate fuel stream that mixes with air in a distributed manner, achieving good mixing without creating the high-velocity central jet that causes flashback
Solution Approach 2:
Rather than increasing fuel jet penetration depth to improve mixing, the invention inverts the approach by using multiple shallow, radially distributed jets that mix fuel and air more effectively through increased surface area and reduced velocity, preventing flashback while maintaining mixing quality
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 configuration achieves more complete combustion, reduces NOx emissions, and allows the turbomachine to operate in a lower turn down mode, enhancing fuel efficiency and reducing the risk of flashback, thus balancing efficiency and emission control.
Implementation Method 1
creating a mixing region that enhances fuel and air mixing
Implementation Method 2
cooling the circumferential wall and tube elements, thereby lowering temperatures and emissions
Implementation Method 3
The turbine converts thermal energy from the high temperature gas stream to mechanical energy that rotates a turbine shaft
Data Source
AI summary
A turbomachine (2) includes a compressor (4), a combustor (6) operatively connected to the compressor (4), an end cover (30) mounted to the combustor (6), and an injection nozzle assembly (38, 39, 40) operatively connected to the combustor (6). The injection nozzle assembly (38, 39, 40) includes a first end portion (80) that extends to a second end portion (82, 166, 224, 324), and a plurality of tube elements (90, 175, 230, 330) provided at the second end portion (82, 166, 224, 324). Each of the plurality of tube elements (90, 175, 230, 330) defining a fluid passage includes a body having a first end section (132, 198, 244, 344) that extends to a second end section (134, 200, 245, 345). The second end section (134, 200, 245, 345) projects beyond the second end portion (82, 166, 224, 324) of the injection nozzle assembly (38, 39, 40).