Asymmetric Base Plate Cooling for Combustor Flashback Prevention

Solution Overview

Problem

Conventional can-annular combustors with alternating swirl mains experience zones of varying fuel richness, leading to increased propensity for flashback and flame holding due to shear and vortices between main burner flows, which results in higher NOx and CO emissions.

Innovation Solution

An optimized cooling arrangement is implemented, where increased cooling air flow is delivered to fuel-rich inbound zones to reduce fuel-to-air mixture levels, while reduced cooling air flow is directed to fuel-lean outbound zones, maintaining overall cooling flow and reducing the likelihood of flashback and flame holding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If alternating swirl directions are used in main burners to reduce shear and vortices, then combustion stability is improved, but fuel-rich zones still create flashback and flame holding risks

Engineering Contradiction:

Improvecombustion stabilityVSAvoidflashback and flame holding risk

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The base plate incorporates regions with different cooling aperture densities: high-density regions positioned to deliver increased cooling air flow to fuel-rich inbound zones, and low-density regions for fuel-lean outbound zones. This local differentiation of cooling intensity addresses the specific flashback risks in fuel-rich zones without compromising combustion stability elsewhere.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cooling system is segmented into multiple regions with distinct aperture densities. The base plate is divided into high-density and low-density cooling regions, each serving specific zones of the combustor. This segmentation allows targeted cooling intervention in fuel-rich areas while maintaining appropriate cooling levels in other regions.

Inventive Principle:

Principle #1Segmentation

2Temperature

If uniform cooling air flow is delivered across all base plate regions, then overall cooling is maintained, but fuel-rich zones remain susceptible to flashback

Engineering Contradiction:

Improveoverall coolingVSAvoidflashback resistance in fuel-rich zones

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The base plate incorporates regions with different cooling aperture densities: high-density regions positioned to deliver increased cooling air flow to fuel-rich inbound zones, and low-density regions for fuel-lean outbound zones. This local differentiation of cooling intensity addresses the specific flashback risks in fuel-rich zones without compromising combustion stability elsewhere.

Inventive Principle:

Principle #3Local quality

3Reliability

If increased cooling air flow is delivered to all zones, then flashback risk is reduced, but engine efficiency decreases due to excessive cooling air consumption

Engineering Contradiction:

Improveflashback preventionVSAvoidcooling air consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The base plate incorporates regions with different cooling aperture densities: high-density regions positioned to deliver increased cooling air flow to fuel-rich inbound zones, and low-density regions for fuel-lean outbound zones. This local differentiation of cooling intensity addresses the specific flashback risks in fuel-rich zones without compromising combustion stability elsewhere.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of applying uniform excessive cooling across all zones, the system applies partial excessive cooling only where needed (fuel-rich inbound zones with high-density apertures). This targeted approach provides sufficient flashback protection in critical areas while avoiding the efficiency penalty of over-cooling fuel-lean zones.

Inventive Principle:

Principle #16Partial or excessive action

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 solution effectively reduces the occurrence of flashback and flame holding, maintaining engine efficiency and minimizing NOx and CO emissions by targeting specific zones with tailored cooling fluid distribution.

Implementation Method 1

increased cooling air flow is delivered to fuel-rich inbound zones to reduce fuel-to-air mixture levels

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

The pilot burner mixture may be swirled by flow control surfaces in the pilot burner that impart circumferential motion to the axially moving pilot burner mixture

Methodology Applied

Scientific EffectSwirling flow: Vortex Ring

Implementation Method 3

the main burner flows and the pilot burner flow blend at which point the main burner flows are ignited by the pilot flame

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentEP3004742B1Asymmetric base plate cooling with alternating swirl main burners

Publication Date: 2019.11.06 SIEMENS AG

Figure 1
Figure 2~3
Figure 4~5

AI summary

A combustor arrangement (10) including: a pilot burner (22) having a pilot cone (62); a plurality of clockwise (130) main swirlers interposed among a plurality of counterclockwise (132) main swirlers and disposed concentrically about the pilot burner; and a base plate (40) transverse to the main swirlers. Inbound-zones (134) exist where adjacent portions (106) of adjacent flows (108) through main swirlers flow toward the pilot cone, and interposed between the inbound zones outbound zones (136) exist where adjacent portions of adjacent flows flow away from the pilot cone. The arrangement is configured to preferentially deliver more cooling fluid to the inbound zones than the outbound zones.