In combustion processes, two extremely harmful pollutants affecting people’s respiratory health are generated:
• Nitrogen oxides (NOx)
• Carbon monoxide (CO)
In addition, when burning diesel sulfur oxide is created, which can create acid rain when combined with nitrogen oxide, a phenomenon extremely harmful to health and to the planet.
Pollutant emissions during the combustion process
During combustion, an oxidation reaction occurs, in which various elements are produced, including carbon dioxide (CO2) and water (H2O).
1. Nitrogen oxide: this is generated when burning the hydrocarbon with air in an industrial burner, which has 21% oxygen and 79% nitrogen.
In this process the nitrogen present does not contribute energy to the combustion reaction, being inert in nature. However, under certain conditions, this element can react with oxygen and form nitrogen oxides.
2. Carbon monoxide: when the fuel is not maximized due to lack of oxygen, poor mixing or low flame temperatures in the burner, this element is formed instead of carbon dioxide (CO2).
Advantages of having low pollutant emissions
Some benefits of reducing these harmful components are as follows:
• A less polluted environment that does not adversely affect people’s health
• Greater use of energy by reducing CO emissions and achieving complete combustion of the fuel
• By reducing sulfur oxide emissions the creation of acid rain is avoided
• By being in compliance with regulations, fines are avoided
• Social and environmental responsibility
Techniques to reduce emissions of NOx pollutants
By decreasing one or more of these three factors it is possible to reduce the emission of pollutants:
1. Flame temperature
2. Oxygen concentration
3. Combustion time
At Nutec Bickley we employ four different techniques that manipulate these elements to reduce NOx emissions:
1. Flue gas recirculation
This incorporates a mechanism to use the combustion gases inside the furnace and recirculate them to cool the flame.
This helps reduce emissions as the flame cools while the oxygen concentration is minimized.
2. Flameless combustion
When the burners identify that the temperature is higher than the auto-ignition point they turn off automatically. At this point they only emit air and gas (without the spark), allowing the flame to occur in the furnace instead of in the burner.
By having the ideal temperature, it is no longer necessary to carry out the process in the burner, which generates a combustion cloud without flame, hence the name ‘flameless combustion’.
3.LNI (low NOx injection)
At Nutec Bickley we have Fives North American LNI technology, which combines the two previous techniques.
When the temperature is found to be above the auto-ignition point, the burners use lances placed strategically in the furnace to increase the recirculation of the gas and to help start combustion.
4.Staged combustion
Combustion is carried out in two stages: at first introducing a small amount of air to start the process and burning the rest later.
This method reduces the concentration of oxygen and residence times, achieving lower temperatures and generating fewer nitrogen oxides.
We are experts in pollutant emissions reduction
At Nutec Bickley we recognize that the authorities are getting stricter in matters related to the environment, so we’re here to help you keep in compliance with the relevant requirements.
We are experts in the process control techniques needed to reduce pollution and we offer the latest combustion technology. Make contact with our expert advice team so that we can help you redesign your processes and operate in a greener way.
