Combustor End Cap Premixer Flow Conditioning
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Solution Overview
Problem
Combustors face challenges in maintaining optimal flow conditions, leading to issues such as flashback, damage from high combustion gas temperatures, increased NOx production, and reduced efficiency during part-load operations, due to stratified flow and local overfed regions.
Innovation Solution
The combustor design includes an end cap with premixer tubes that extend radially across the combustor, featuring slots or apertures to condition the flow, reducing mass flow rates in high flow regions and normalizing fluid distribution, along with a shroud defining a fuel plenum to mix fuel and working fluid effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If higher combustion gas temperatures are used, then thermodynamic efficiency is improved, but flashback risk and damage to nozzles increase
Solution Approach 1:
The combustor design incorporates flow conditioning means upstream in the premixer tubes to pre-condition the working fluid flow before it reaches the combustion zone. This preliminary flow conditioning ensures uniform velocity distribution and prevents localized high-velocity regions that could cause flashback, thereby enabling operation at higher temperatures for improved efficiency while maintaining safety
Solution Approach 2:
The flow conditioning means creates locally optimized flow conditions within the premixer tubes by addressing stratified flow patterns in specific regions. By normalizing flow velocity distribution in high-flow regions without restricting overall flow, the design allows higher combustion temperatures for efficiency while preventing flashback in vulnerable areas
2Use of energy by moving object
If higher combustion gas temperatures are used, then thermodynamic efficiency is improved, but nitrogen oxide production increases
Solution Approach 1:
By pre-conditioning the working fluid flow upstream through the flow conditioning means, the combustor achieves more uniform combustion characteristics. This preliminary action ensures that fuel and air are evenly mixed and distributed before combustion, allowing efficient combustion at optimized temperatures while reducing localized hot spots that generate excessive NOx
3Object-generated harmful factors
If reduced fuel flow is used for part load operation, then emissions are reduced, but chemical reaction rates decrease leading to increased carbon monoxide and unburned hydrocarbons
Solution Approach 1:
The flow conditioning means addresses local flow stratification issues within the premixer tubes by normalizing velocity distribution in specific regions. This ensures that even at reduced fuel flow rates for part-load operation, the fuel and air are uniformly mixed and distributed, maintaining adequate chemical reaction rates throughout the combustion chamber while still reducing overall emissions
Solution Approach 2:
The flow conditioning means modifies the flow parameters (velocity distribution, flow uniformity) of the working fluid before combustion. By changing these flow parameters to achieve more uniform distribution, the combustor maintains effective chemical reaction rates at part-load conditions while controlling emissions
4Device complexity
If conventional combustor design is used, then结构简单性 is maintained, but flow stratification causes local overfed regions and reduced efficiency
Solution Approach 1:
The flow conditioning means is integrated within the existing premixer tube structure, segmenting the flow path into conditioned and unconditioned regions. This segmentation approach allows flow normalization in critical areas without requiring complete redesign of the entire combustor, maintaining structural simplicity while improving efficiency
Solution Approach 2:
The flow conditioning means is combined with the existing premixer tube structure rather than being a separate component. By merging the flow conditioning function into the premixer tubes, the design improves combustor efficiency while minimizing additional structural complexity
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 enhances thermodynamic efficiency, reduces the risk of flashback, minimizes undesirable emissions, and protects the combustor by normalizing flow across the combustor, improving performance across various operating levels.
Implementation Method 1
means for conditioning flow through the plurality of premixer tubes
Data Source
AI summary
A combustor includes an end cap that extends radially across a portion of the combustor and includes an upstream surface axially separated from a downstream surface. A combustion chamber is downstream of the end cap. Premixer tubes extend from a premixer tube inlet proximate to the upstream surface through the downstream surface to provide fluid communication through the end cap and include means for conditioning flow through the plurality of premixer tubes. A method for conditioning flow through a combustor includes flowing a working fluid through a first and second set of premixer tubes that extend axially through an end cap, wherein the second set of premixer tubes includes means for conditioning flow through the second set of premixer tubes, and flowing a fuel through the first or second set of premixer tubes.