Gas Turbine Combustor Pilot Nozzle Air Blast Atomization
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Solution Overview
Problem
In dual fuel combustion low NOx combustors of gas turbines, high pilot ratios during light load operations lead to the generation of smoke due to the use of pressure spraying type nozzles for liquid fuel injection, causing combustion instability and pollution.
Innovation Solution
The implementation of an air blast method using combustion air to atomize liquid fuel in the pilot nozzle, with a gas nozzle portion for gaseous fuel and a liquid nozzle portion formed in an annular shape, featuring first and second air blast nozzle portions to generate air blasts along the inner and outer surfaces of the liquid film, promoting atomization and evaporation for stable combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pressure spraying type nozzle is used for liquid fuel injection in the pilot nozzle, then the liquid fuel can be injected into the combustion zone, but smoke is generated during light load operations due to insufficient atomization at high pilot ratios
Solution Approach 1:
The liquid fuel injection is segmented into multiple injection points around the circumferential direction, with liquid fuel injection holes arranged in the circumferential direction of the nozzle body. This segmentation allows for more uniform distribution and better atomization of liquid fuel, preventing smoke generation while maintaining combustion stability.
Solution Approach 2:
Different regions of the nozzle are given different functions: the center portion injects liquid fuel through multiple circumferentially arranged holes for atomization, while the outer periphery injects gaseous fuel. This local differentiation optimizes atomization quality in the liquid fuel region while maintaining overall combustion stability.
2Device complexity
If a pressure spraying type nozzle is used for liquid fuel injection, then the nozzle structure is simple, but the atomization effect is insufficient leading to poor combustion stability at high pilot ratios
Solution Approach 1:
The nozzle structure is segmented with multiple liquid fuel injection holes arranged circumferentially around the nozzle body centerline. This segmentation provides effective atomization without requiring complex external atomizing devices, thus maintaining structural simplicity while improving combustion stability.
Solution Approach 2:
The nozzle utilizes the kinetic energy of the injected liquid fuel itself to achieve atomization through the circumferential hole arrangement, leveraging fluid dynamics principles rather than requiring additional mechanical or pneumatic atomizing components.
3Adaptability or versatility
If only a single type of fuel injection is used, then the fuel system is simple, but the versatility of fuel selection is limited
Solution Approach 1:
The nozzle is designed with multi-functionality to inject both liquid fuel (through circumferential holes in the nozzle body) and gaseous fuel (through the outer periphery), allowing the gas turbine to operate with different fuel types or combinations. This universal design enables flexible fuel selection without requiring separate nozzles for each fuel type.
Solution Approach 2:
The nozzle structure allows dynamic selection and combination of fuel types by controlling which injection paths are activated. The design enables transition between liquid-only, gaseous-only, or combined fuel injection modes, providing operational flexibility while maintaining a single integrated nozzle structure.
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 approach effectively suppresses smoke generation during light load operations by ensuring stable combustion and minimizing pollution, even at high pilot ratios, by enhancing the atomization and evaporation of liquid fuel through the air blast method.
Implementation Method 1
throws the combustion air at a liquid film formed in the liquid nozzle portion to atomize the liquid fuel by use of a velocity difference between the combustion air and the liquid film
Implementation Method 2
promoting atomization and evaporation for stable combustion
Data Source
AI summary
This invention aims to suppress the occurrence of smoke, for example, during a light load operation of a gas turbine, by adopting an air blast method for a pilot nozzle in a dual fuel combustion low NOx combustor. A gas turbine combustor of the present invention is that in a gas turbine furnished with a dual fuel combustion low NOx combustor having a pilot nozzle capable of injecting a gaseous fuel and a liquid fuel simultaneously or selectively, and a plurality of main nozzles disposed around the pilot nozzle and being capable of injecting a gaseous fuel and a liquid fuel simultaneously or selectively, wherein the pilot nozzle has a gas nozzle portion for injecting the gaseous fuel, and a liquid nozzle portion for injecting the liquid fuel, adopts an air blast method for the liquid nozzle portion, uses combustion air as air for an air blast, and throws the combustion air at a liquid film formed in the liquid nozzle portion to atomize the liquid fuel by use of a velocity difference.