Coal Nozzle Tip with Diverging Channels and Obstructions
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Solution Overview
Problem
Existing coal nozzle tip assemblies for steam generation systems suffer from inefficient mixing of pulverized coal particles and primary air, leading to reduced burning efficiency and increased pollutant emissions, particularly NOx, due to aggregation of particles and sub-optimal air-fuel mixture before combustion.
Innovation Solution
A coal nozzle tip assembly with diverging channels and obstructions at the exit faces to promote turbulence and improve mixing, eliminating the need for an outer shroud for secondary air and allowing for a larger cross-sectional area, which enhances combustion efficiency and reduces pressure drop, while incorporating a catalyst for further NOx reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flat guide vanes are used to direct the flow of primary air and coal particles, then the flow direction is controlled, but the mixing of coal particles and primary air remains sub-optimal
Solution Approach 1:
The nozzle tip is divided into multiple channels (2-4 channels) that diverge from each other, with each channel containing obstructions. This segmentation creates multiple flow paths that enhance mixing between coal particles and primary air, resolving the contradiction by maintaining flow direction control while significantly improving combustion efficiency through turbulent mixing in each channel.
Solution Approach 2:
Obstructions are introduced as intermediary elements within each channel to promote turbulence and mixing. These obstructions act as mediators that enhance the interaction between coal particles and primary air without requiring complex external mixing devices, thus improving combustion efficiency while maintaining operational simplicity.
2Ease of manufacture
If the nozzle tip assembly is designed with simple structure, then manufacturing and maintenance are easier, but the ability to handle non-homogenous mixture is limited
Solution Approach 1:
The nozzle tip is segmented into multiple diverging channels with obstructions, creating a complex flow pattern within a relatively simple overall structure. This segmentation enables effective handling of non-homogenous coal-air mixtures while maintaining ease of manufacture through modular channel design and simple obstruction elements.
Solution Approach 2:
The channel geometry parameters (divergence angle, obstruction position and shape) are optimized to enhance mixing capability without complicating the overall structure. By carefully selecting these parameters, the nozzle achieves superior mixture handling performance while remaining simple to manufacture and maintain.
3Productivity
If outer shroud for secondary air is included, then combustion support is improved, but the device complexity and space requirements increase
Solution Approach 1:
The outer shroud for secondary air delivery is completely removed from the nozzle tip assembly. Instead, secondary air is introduced separately at a distance from the nozzle tip through other means. This extraction of the shroud element simplifies the nozzle structure and reduces space requirements while maintaining combustion support functionality through alternative secondary air introduction methods.
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 solution achieves improved combustion efficiency, reduced pollutant emissions, and flexibility in operation, enabling stable flame attachment and efficient steam generation across varying loads without additional energy support, while maintaining a simple and durable design.
Implementation Method 1
an obstruction is disposed in the exit faces of the channels... This aggressively promotes the flame attachment and devolatization near the exit faces of the coal nozzle tip assembly
Implementation Method 2
incorporating a catalyst for further NOx reduction
Data Source
AI summary
A steam generating system includes a furnace, a nozzle tip assembly for pulverized coal and primary air as well as means for conveying secondary air in the furnace. The nozzle according to the invention comprises a nozzle body (3) and several channels (5) being connected with the nozzle body, the channels are diverging from each other. At the exit faces (17) of the channels obstructions (13) are disposed to induce huge turbulences of the primary air when entering the furnace. Due to these turbulences the primary air and the entrained coal are mixed very well before being combusted in the furnace. This results in a better more effective combustion with reduced NOx-emissions.