Hydrogen Gas Turbine Combustor Sizing for Low-NOx Combustion
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Solution Overview
Problem
Hydrogen fuel poses challenges in gas turbine engines due to its high reactivity, leading to increased NOx emissions and the need for reduced combustor residence time, which existing combustors designed for hydrocarbon fuels fail to address effectively.
Innovation Solution
Designing a variety of combustors with different shapes and sizes to meet NOx emission targets by reducing combustor residence time, utilizing hydrogen fuel without diluents, and incorporating fuel nozzle assemblies that promote rapid fuel-air mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If existing combustors designed for hydrocarbon fuels are used with hydrogen fuel, then the combustor structure can be maintained, but NOx emissions increase due to high reactivity and extended residence time
Solution Approach 1:
The patent applies parameter changes by modifying the combustor's physical dimensions (length, volume, cross-sectional area) to reduce residence time. Specific parameter relationships are established: combustor length L ≤ 0.05 × (mass flow rate of compressed air)^0.5, and combustor volume V ≤ 0.003 × (mass flow rate of compressed air)^0.5. These parameter changes directly address the contradiction by reducing the time hydrogen fuel remains in the combustor, thereby reducing NOx emissions while maintaining stable combustion.
2Object-generated harmful factors
If combustor size is reduced to reduce residence time and NOx emissions, then emission targets are met, but combustion stability may be compromised
Solution Approach 1:
The patent establishes specific parameter ranges and relationships that balance emission reduction with combustion stability. The combustor cross-sectional area A is constrained by A ≥ 0.0006 × (mass flow rate of compressed air)^0.5, ensuring sufficient mixing area. The length-to-area ratio is controlled by L/A ≤ 0.1 × (mass flow rate of compressed air)^-0.5, maintaining appropriate residence time. These parameter changes resolve the contradiction by defining a feasible design space that simultaneously achieves low NOx emissions and stable combustion.
Solution Approach 2:
The patent incorporates feedback mechanisms through fuel nozzle assemblies that promote rapid fuel-air mixing. The fuel nozzle design includes specific geometric parameters (orifice diameter, convergence angle, length-to-diameter ratio) that optimize mixing efficiency. This feedback control of the fuel-air mixture quality ensures stable combustion even in the reduced combustor environment, while the overall combustor sizing maintains residence time below thresholds that would generate excessive NOx.
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
The proposed combustor designs effectively reduce NOx emissions and achieve efficient combustion of hydrogen fuel, aligning with emission targets while maintaining engine performance.
Implementation Method 1
a combustor configured to combust a mixture of the hydrogen fuel and the compressed air
Data Source
AI summary
A gas turbine engine includes a hydrogen fuel delivery assembly configured to deliver a hydrogen fuel flow, a compressor section configured to compress air flowing therethrough to provide a compressed air flow, and a combustor including a combustion chamber having a burner length and a burner dome height. The combustion chamber is configured to combust a mixture of the hydrogen fuel flow and the compressed air flow. The combustion chamber can be characterized by a combustor size rating between one inch and seven inches. In more detail, the combustion chamber can be characterized by the combustor size rating between one inch and seven inches at a core air flow parameter between two and one half kN and sixty kN, in which the combustor size rating is a function of the core air flow parameter.