Cyclic Burner Combustion for NOx Reduction
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Solution Overview
Problem
Existing methods for reducing NOx emissions in combustion processes, such as forced oscillating combustion, are not of practical value and do not achieve significant NOx reduction.
Innovation Solution
A burner combustion method where the flow rate of a fuel fluid and an oxidant fluid are cyclically changed, along with the concentration of oxygen in the oxidant fluid, to create a cyclical oscillation state in the burners, with a phase difference between the oscillation states of opposing burners, effectively reducing NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If forced oscillating combustion is applied to reduce NOx emissions, then NOx reduction is achieved to some degree, but the method is not of practical value and does not achieve significant NOx reduction
Solution Approach 1:
The patent applies periodic action by cyclically changing the flow rates of fuel fluid and oxidant fluid supplied to multiple burners, creating forced oscillating combustion. The flow rates are varied in a periodic manner with phase differences between opposing burners, causing the combustion state to oscillate between fuel-rich and fuel-lean conditions. This periodic modulation of combustion parameters significantly reduces NOx emissions by preventing sustained high-temperature combustion that produces thermal NOx, while maintaining practical effectiveness through coordinated control of multiple burners.
Solution Approach 2:
The patent implements dynamics by transitioning from static combustion conditions to dynamic oscillating combustion. The flow rates of fuel and oxidant are continuously varied in a cyclic manner, creating time-dependent combustion states. This dynamic approach allows the combustion system to alternate between different fuel-to-oxidant ratios, preventing the formation of stable high-temperature zones that generate thermal NOx, thereby achieving significant and practical NOx reduction.
2Ease of operation
If multiple burners are operated with cyclical oscillation states, then combustion control is improved, but coordination and control complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the combustion system into multiple independent burners, each capable of operating with its own cyclical oscillation state. Opposing burners are controlled with phase differences, allowing independent optimization of each burner's combustion characteristics. This segmentation enables flexible control where each burner can be adjusted individually while contributing to the overall NOx reduction goal, simplifying the control strategy compared to managing a single complex combustion zone.
Solution Approach 2:
The patent implements asymmetry by introducing phase differences between opposing burners in the cyclical oscillation control. Instead of synchronizing all burners identically, opposing burners operate with deliberately asymmetric timing, where one burner is in a fuel-rich state while its opposite is in a fuel-lean state. This asymmetric control creates complementary combustion patterns that enhance NOx reduction effectiveness while maintaining manageable control complexity through systematic phase offsetting.
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 method significantly and reliably reduces NOx emissions, applicable to both new and existing heating furnaces, while maintaining constant pressure and optimizing combustion conditions.
Implementation Method 1
cyclically changing the flow rate of a fuel fluid and the flow rate of an oxidant fluid supplied to the respective burners, whereby, the burners are made to cause combustion in a cyclical oscillation state
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4(a)~4(b)
AI summary
A burner combustion method is employed in which at least two burners (2) are disposed opposite each other in a furnace (1) so as to cause combustion, the method comprising: cyclically changing at least one of a flow rate of a fuel fluid and a flow rate of an oxidant fluid supplied to the respective burners (2) while cyclically changing a concentration of oxygen in the oxidant fluid thereby cyclically changing an oxygen ratio obtained by dividing a supply oxygen amount by a theoretically required oxygen amount, whereby, the burners (2) are made to cause combustion in a cyclical oscillation state, wherein with respect to the cyclical change in an oscillation state of the burners (2), a phase difference is provided between a cyclical change in an oscillation state of at least one burner (2) and cyclical changes in oscillation states of other burners (2).