Pulsating Solid Fuel Burner for Low NOx Emissions
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Solution Overview
Problem
Solid fuel burners, particularly in part-load operations, experience incomplete combustion leading to high nitrogen oxide (NOx) emissions and unstable ignition processes, resulting in increased pollution levels.
Innovation Solution
A solid fuel burner with a primary air supply device and fuel supply device that creates a pulsating air/fuel mixture, using a control device to vary the fuel content cyclically and adjust the primary air supply, which is transported to an orifice for combustion, reducing NOx emissions and improving combustion intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fuel supply is throttled to operate under partial load conditions, then power output is reduced, but incomplete combustion occurs leading to high nitrogen oxide emissions and unstable ignition processes
Solution Approach 1:
The patent applies periodic action by pulsating the fuel supply to the burner at frequencies between 0.5 Hz and 1 Hz. This periodic modulation of the fuel-air mixture creates cyclic combustion intensification that maintains stable ignition and complete combustion even at reduced power output, thereby preventing high nitrogen oxide emissions during part-load operation while preserving the desired power reduction
2Productivity
If additional air is fed into the lance to accelerate combustion, then combustion intensity increases, but the complexity of the air supply system increases
Solution Approach 1:
The patent merges the primary air supply with the pulsating fuel supply mechanism, using the same pulsating action to modulate both fuel delivery and air mixing. This integration eliminates the need for separate additional air supply systems while maintaining high combustion intensity through synchronized pulsating injection of fuel-air mixture at optimized frequencies
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 pulsating operation effectively lowers NOx concentrations to below a quarter of non-pulsating levels, maintains low CO emissions, and enhances heat transfer, allowing for cost savings by reducing the need for denitrification catalysts and improving flame stability and efficiency.
Implementation Method 1
fuel is metered into the combustion chamber in a pulsating manner... a pulsating content of fuel in the primary air is generated
Implementation Method 2
combustion of pulverized, solid fuels... after ignition a flame is formed that extends from the orifice into the combustion chamber and ignites a boiler surrounding or connected to the combustion chamber
Data Source
Figure 1~2
Figure 3~4c
Figure 5~6
AI summary
The invention relates to a solids burner (1) for a combustion chamber (3) for the combustion of pulverised solid fuels (11), and to a method for the operation thereof, having a primary air feed device and a fuel feed device for producing an air/fuel mixture composed of primary air (11) and fuel (10), and having at least one lance (5) which transports the air/fuel mixture to a mouth opening (2). To enable the solids burner (1) to be operated with low nitrogen oxide emissions, there is provided upstream of the mouth opening (2) a control device (23) which adjusts a content of fuel (10) contained in the air/fuel mixture in pulsating fashion over time.