Dual Fuel Gas Turbine Combustor Flame Stability

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Solution Overview

Problem

Gas turbines face challenges in stably burning low BTU gases like blast furnace gas and biomass gasified gas due to their low flame temperature and burning velocity, requiring additional fuels for startup and carburetion to maintain combustion stability and reduce NOx emissions.

Innovation Solution

A gas turbine combustor design with a burner featuring a first swirler with alternately formed gas and air holes, and a swiveling flow path that includes a second gas hole for high BTU gas supply, allowing for improved flame holding and air distribution, enabling stable combustion of both low and high BTU gases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If low BTU gas is used as primary fuel, then NOx emissions are reduced, but combustion stability deteriorates due to low flame temperature and burning velocity

Engineering Contradiction:
ImproveNOx emissionsVSAvoidcombustion stability
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent combines low BTU gas and high BTU gas supply paths into a single burner structure with integrated swirlers. The first swirler receives both low BTU gas (through first gas holes) and high BTU gas (through second gas holes formed in the swiveling flow path), allowing synergistic combustion where high BTU gas enhances flame stability while low BTU gas contributes to low NOx emissions

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The burner structure is designed to handle multiple fuel types simultaneously. The first swirler with alternately arranged first gas holes and air holes, combined with second gas holes in the swiveling flow path, creates a universal combustion system that can stabilize flames from low BTU gases while maintaining the ability to burn high BTU gases efficiently

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Temperature

If volumetric fuel flow of low BTU gas is increased to achieve equivalent combustor exit temperature, then combustion temperature is improved, but device complexity increases

Engineering Contradiction:
Improvecombustor exit temperatureVSAvoidfuel supply system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent merges the fuel supply paths for low BTU gas and high BTU gas into a single integrated burner structure. By forming second gas holes in the swiveling flow path of the first swirler, the design eliminates the need for separate burner systems, reducing overall device complexity while achieving the required combustor exit temperature through combined fuel injection

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If separate high calorific fuel path is provided for startup, then combustion stability during startup is improved, but device complexity increases

Engineering Contradiction:
Improvestartup combustion stabilityVSAvoidfuel path complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the high BTU gas supply path directly into the first swirler structure by forming second gas holes in the swiveling flow path. This eliminates the need for a completely separate high calorific fuel path, reducing device complexity while maintaining startup combustion stability through the availability of high BTU gas in the same burner assembly

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The first swirler is designed with dual fuel supply capability - first gas holes for low BTU gas and second gas holes for high BTU gas. This multi-functional design allows the same burner structure to handle both startup (using high BTU gas) and steady-state operation (using low BTU gas), simplifying the overall fuel path configuration

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 flame holding performance and combustion stability, particularly during multi-fuel operations, reducing air insufficiency and CO emissions, and allows for efficient use of low BTU gases as primary fuel while supporting high BTU gas startup.

Implementation Method 1

a swiveling flow path is formed in the gas hole and the air hole in the burner to swivel the gas and the air and supply the gas and the air to the interior of the combustion chamber

Methodology Applied
Scientific EffectSwirling flow: Vortex Ring

Implementation Method 2

to hold a flame, it is generally necessary to form a recirculation zone in the vicinity of the center in radial directions of the burner and give thermal energy to air and a fuel jetted from the burner

Methodology Applied
Scientific EffectRecirculation: Convection

Implementation Method 3

a combustion chamber for mixing a gas and air together to burn the gas

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 4

mixing a gas and air together to burn the gas

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP2706295B1Dual fuel gas turbine combustor for low heating value fuel
Publication Date: 2016.03.09 MITSUBISHI HITACHIPOWER SYST LTD
  • EP2706295B1 patent drawingFigure 1
  • EP2706295B1 patent drawingFigure 2~3
  • EP2706295B1 patent drawingFigure 4~5

AI summary

A gas turbine combustor (3) having a combustion chamber (12) for mixing a low heating value fuel gas (60) and air (102) together to burn the gas (60), and a burner (300) disposed upstream of the combustion chamber (12) for supplying a gas (60) and air (102) to an interior of the combustion chamber (12) to hold a flame, wherein: the burner (300) is provided with a first swirler (201) in which gas holes (401) and air holes (402) are alternately formed in a circumferential direction thereof; a first gas (60) is supplied to the gas holes (401) in the first swirler (201) and air (102) is supplied to the air holes (402); and a swiveling flow path is formed in each gas hole (401) and each air hole (402) in the burner (300) to swivel the gas (60) and the air (102) and supply the gas (60) and the air (102) to the interior of the combustion chamber (12), a second gas hole (500) is formed in the swiveling flow path in at least one of the air holes (402) and the gas holes (401), and a second high heating value fuel gas (80) is supplied through the second gas hole (500).