Fuel Nozzle Splitter Layout for Internal Flame Holding
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Solution Overview
Problem
Existing combustion burners with comb-shaped splitters either promote external ignition, leading to increased NOx production, or inhibit low NOx combustion due to air injection, failing to enhance flame holding performance effectively.
Innovation Solution
A combustion burner design featuring slitted and non-slitted splitters within the fuel nozzle, where the slitted splitters increase edge length for enhanced flame holding and the non-slitted splitters guide fuel to the slitted ones, preventing air injection and promoting internal flame holding, while inclined surfaces and flow straightening plates minimize external ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the number of splitters is increased to enhance flame holding performance, then the edge length of splitter length is increased, but the blocking rate of the outlet of the burner is increased and pressure loss is increased
Solution Approach 1:
The splitter is configured with a widened portion that increases in width in the flow direction, transforming the traditional uniform cross-section splitter into a three-dimensional structure with variable dimensions. This dimensional change allows the splitter to provide sufficient edge length for flame holding while occupying less cross-sectional area, thereby reducing blocking rate and pressure loss
2Length of stationary object
If the number of splitters is increased while reducing width to ensure edge length, then the splitters are disposed close to the wall portion of the fuel nozzle, but ignition occurs at the outer periphery of the fuel nozzle
Solution Approach 1:
The splitter employs an asymmetric configuration with a widened portion that is broader at the upstream end and tapers toward the downstream end. This asymmetric shape allows the splitter to maintain sufficient edge length for flame holding while positioning the bulk of its structure away from the wall portion, preventing external ignition at the outer periphery of the fuel nozzle
3Productivity
If air is injected from the splitter to promote combustion, then combustion in the fuel nozzle is promoted, but reduced combustion is inhibited and low NOx combustion cannot be realized
Solution Approach 1:
The air injection function is completely removed from the splitter structure. The splitter is designed solely for flow division and flame holding purposes, extracting the harmful air injection function that caused excessive combustion promotion and NOx generation, while retaining the beneficial flame holding capability
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 achieves improved flame holding performance and low NOx combustion by internal flame holding, reducing NOx generation and enhancing fuel guidance within the nozzle.
Implementation Method 1
a recirculation region is formed on a downstream side of the splitters to maintain combustion of pulverized coal
Implementation Method 2
combustion performed in a fuel nozzle
Implementation Method 3
internal flame holding where a flame is held on the inside of the fuel nozzle is strengthened
Data Source
AI summary
A combustion burner includes a plurality of splitters (5), (6), (7) configured to divide a fuel gas flow by a widened portion where a width of the widened portion increases as the widened portion extends in the direction of the fuel gas flow. The splitters include: slitted splitters (5), (6) configured to slits (SL) at a downstream end in the fuel gas flow; and non-slitted splitters (7) configured to adjacently to the slitted splitters (5), (6), each of the non-slitted splitters (7) configured to the widened portion at a downstream end in the fuel gas flow, and configured to a fixed width in a direction of the longitudinal axis.