Burner Pilot Fuel Injection for Flame Stability
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Solution Overview
Problem
Premix burners tend to become unstable under low-load or transient conditions, leading to quench pulsations and overheating issues due to uneven fuel distribution and cooling, which complicates the operation and maintenance of heat generators.
Innovation Solution
A burner design incorporating a pressure swirl nozzle for liquid pilot fuel injection, integrated into the burner front plate, allows for stable operation with improved atomization and cooling, enabling modular construction and reducing overheating risks by directing the fuel injection away from the burner outlet edge and utilizing purging air for efficient atomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If premix burners are operated under low-load or transient conditions, then fuel consumption is reduced, but flame stability deteriorates leading to quench pulsations
Solution Approach 1:
The burner system is segmented into a main premix burner and a separate pilot burner with liquid fuel injection. The pilot burner operates independently to stabilize the flame during low-load conditions, while the main burner handles the primary combustion. This segmentation allows the system to maintain reliability across varying load conditions.
Solution Approach 2:
A liquid pilot fuel is introduced as an intermediary substance to stabilize the combustion process during transient and low-load conditions. The pilot fuel creates a stable reference flame that prevents quench pulsations in the main premix burner, enabling reliable operation across the full load range.
2Reliability
If liquid pilot fuel is injected close to the burner outlet edge, then flame stability is improved, but overheating of components occurs
Solution Approach 1:
The nozzle is positioned in the radially outer region of the burner front plate, creating a localized fuel injection zone that is spatially separated from the central high-temperature region at the burner outlet. This local quality differentiation allows the pilot fuel to stabilize the flame edge without exposing the nozzle to excessive temperatures.
Solution Approach 2:
The fuel injection location is moved from the axial dimension (close to outlet edge) to the radial dimension (outer region of front plate). This dimensional shift maintains flame stabilization effectiveness while reducing thermal exposure to the nozzle and surrounding components.
3Ease of repair
If the burner design is made modular for easy maintenance, then ease of repair is improved, but device complexity increases
Solution Approach 1:
The burner is divided into distinct modular components: the main premix burner assembly and the pilot burner assembly with liquid fuel injection. The pilot burner elements (nozzle, fuel line, injection system) are separate replaceable modules that can be serviced independently, simplifying maintenance while managing overall system 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
The design ensures stable operation with low pollutant values, prevents overheating, and allows for cost-effective maintenance by enabling easy replacement of pilot burner elements, while maintaining efficient heat generation and flame stability across varying load conditions.
Implementation Method 1
at least one pressure swirl nozzle for feeding liquid pilot fuel
Implementation Method 2
a mixing path is arranged downstream of the swirler
Implementation Method 3
a swirler for a combustion air flow
Implementation Method 4
enabling modular construction and reducing overheating risks by directing the fuel injection away from the burner outlet edge and utilizing purging air for efficient atomization
Data Source
AI summary
A burner (23) for operating a heat generator includes a swirler (2) for a combustion air flow (9), and also devices (7, 12) for injecting at least one fuel into the combustion air flow (9), wherein a mixing path (3) is arranged downstream of the swirler (2), and wherein at least one nozzle (20) for feeding liquid pilot fuel is arranged in the region radially outside the discharge opening of the mixing path (3) of the burner. With such a burner, an operating mode which is as pollutant-free and overheating-free as possible can be enabled even at low load and under transient conditions if the at least one nozzle (20) is arranged in a burner front plate (32), wherein at least one discharge opening (15), through which the pilot fuel discharges into the combustion chamber (16), is provided in a front face (34) of the burner front plate (32), which is arranged essentially parallel to a combustion chamber rear wall (28).