Burner Automation for Low NOx and CO Emissions
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Solution Overview
Problem
Industrial burners struggle to maintain a stoichiometric air-fuel ratio and achieve low residual oxygen levels in flue gases, making it difficult to effectively reduce nitrogen oxides (NOx) and carbon monoxide (CO) emissions using existing automation and catalytic converter systems.
Innovation Solution
A feedback-based system adjusts the fuel and air ratio in the burner's mixing zone, using lambda sensors to measure residual oxygen and control the air/fuel ratio, with supplementary air delivery between catalytic zones to maintain low NOx and CO levels, achieving a stoichiometric oxygen-to-carbon ratio and reducing emissions to 0-9 ppm NOx and 0-100 ppm CO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal combustion is conducted at high temperature to reduce unburned hydrocarbons and carbon monoxide, then combustion completeness improves, but nitrogen oxide emissions increase
Solution Approach 1:
The combustion process is divided into two distinct zones: a first combustion zone where fuel burns at high temperature to ensure complete combustion and minimize CO and unburned hydrocarbons, and a second combustion zone where the flameless combustion occurs at lower temperature to reduce NOx formation. This spatial segmentation allows each zone to optimize for its specific function without compromising the other.
Solution Approach 2:
Different regions of the combustion system are provided with different oxygen concentrations and combustion conditions. The first combustion zone operates with controlled oxygen supply for high-temperature combustion, while the second zone introduces additional oxygen to enable flameless combustion at lower temperatures. This local differentiation of combustion conditions allows simultaneous achievement of complete combustion and low NOx emissions.
2Object-generated harmful factors
If excess air is reduced to lower nitrogen oxide emissions, then NOx formation decreases, but residual oxygen level increases and combustion efficiency drops
Solution Approach 1:
The system maintains continuous combustion in two zones, ensuring that fuel is completely consumed throughout the process. The first zone provides high-temperature combustion to break down fuel molecules, while the second zone continues the combustion process with additional oxygen, ensuring complete oxidation of remaining combustibles. This continuous two-stage combustion eliminates the need for high excess air while maintaining high combustion efficiency.
3Object-generated harmful factors
If stoichiometric air-fuel ratio is maintained to reduce emissions, then NOx and CO levels decrease, but control precision and automation complexity increase
Solution Approach 1:
The burner automation system incorporates feedback control that continuously monitors combustion parameters and adjusts the air-fuel ratio in both combustion zones to maintain stoichiometric conditions. The system dynamically balances the oxygen supply to the first and second combustion zones, ensuring optimal emissions performance while automatically compensating for variations in fuel composition and combustion conditions.
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 system consistently maintains low NOx and CO levels in flue gases, achieving emissions below 0.025% prior to the catalytic converter, enhancing burner efficiency and maintaining emissions at extremely low levels, with a stoichiometric oxygen-to-carbon proportion of 0.5/1 mole/mole.
Implementation Method 1
placing a catalytic converter in a combustion chamber, such as a boiler or flue gas conduit... for the reduction of pre-combustion-generated NOx's
Implementation Method 2
for the oxidation of hydrocarbon and carbon monoxide emissions
Implementation Method 3
a lambda sensor that measures the amount of residual oxygen in flue gases
Data Source
Figure 1
Figure 2A
Figure 2B~3
AI summary
The invention relates to an arrangement for adjusting the ratio between supplied amounts of fuel (PA) and air (I) in a burner (100), which is intended for a gaseous and/or liquid fuel, said burner comprising a fuel and air mixing zone, a fuel supply conduit (210) which is adapted to supply the mixing zone with a given inlet flow of fuel, as well as a combustion air supply means which is adapted to supply the mixing zone with a given inlet flow of combustion air, as well as burner automation which contains measuring instruments (6), said burner having its mixing zone accompanied by a combustion chamber which is in communication with a flue gas conduit, said combustion chamber or flue gas conduit being provided with at least one catalytic zone (40). In the arrangement, - the measuring instruments (6) include at least one sensor (63), such as a lambda sensor, measuring the amount of residual oxygen in flue gases (flue gas oxidation/reduction potential), - the adjustment for an inlet flow (QI, QItot) of combustion air generated by the combustion air (I) supply means (determined as a volume flow per unit time), as well as the adjustment for an inlet flow (QPA, QPAtot) of fuel arriving in the mixing zone by way of the fuel supply conduit (210) (determined as a volume flow per unit time), by means of burner automation (5, 6, 7), is based on the amount of residual oxygen measured from flue gases (S) with the measuring instrument (63), by way of which the burner automation adjusts the relative ratio between said inlet flow (QI, QItot) of combustion air as well as the inlet flow (QPA, QPAtot) of fuel in such a way that the amount of residual oxygen is within the range of 0-0.95%, preferably within the range of 0.05-0.5% in flue gases prior to the catalytic zone (40).