Reduction of CO, HCHO and VOC emissions in your roasting process.
Exhaust gas aftertreatment, in particular the right catalytic converter, for coffee roasting systems and coffee roasters is an important issue, as the roasting process releases significant emissions of pollutants. These emissions include smoke, formaldehyde and other volatile organic compounds (HCHO, VOC), carbon monoxide (CO), nitrogen oxides (NOx) and odor in the form of polycyclic aromatic hydrocarbons (PAH)which can affect both the environment and human health.
Emissions during coffee roasting are significantly influenced by the degree of roastingthe roasting process and the type of coffee bean influenced. Darker roasts and beans with a high oil content, such as Robusta, tend to lead to higher emissions of VOCs and carbon monoxide. Modern roasting processes and Emission reduction technologies from Emission Partner can significantly reduce these emissions.
Exhaust emissions from coffee roasters
Smoke
Aerosols produced during the roasting process.
Formaldehyde and other volatile organic compounds (VOC)
These are mainly produced by the pyrolysis of organic substances in coffee.
Carbon monoxide (CO)
Due to incomplete combustion and the release of gases from the coffee bean.
Nitrogen oxides (NOx)
These are mainly produced at high temperatures or during the oxidation of caffeine.
Odorants
Roasting releases strong-smelling substances that can often be unpleasant.
environmental aspects and regulations
Emissions from coffee roasting plants are subject to strict environmental regulations, depending on the size of the roasting plant and local legislation. In Germany, for example, the TA Luft(Technical Instructions on Air Quality Control) sets out the permissible emission values for installations.
Limit values from the TA Luft for roasting plants:
- Formaldehyde: <15mg/Nm³
- NOx: <350 mg/Nm³
Generally applicable for inorganic substances (with thermal post-combustion):
- CO: < 100 mg/Nm³ with TNV or catalytic converter
- NOx: < 100 mg/Nm³
Unless the raw gas for post-combustion is already more polluted, in which case a maximum of 350 mg/Nm³ applies again (individual case treatment). Generally valid for organic substances :
- Total C: < 50 mg/Nm³ & VOC: < 20 mg/Nm
exhaust gas aftertreatment during coffee roasting
Various exhaust gas aftertreatment methods are used to reduce these pollutants. Particularly relevant are catalytic methodsas they enable efficient pollutant reduction.
Catalytic oxidation
- Functionality: Catalytic oxidation works at lower temperatures (approx. 300-400 °C) and uses a catalyst (often precious metals such as platinum or palladium) to accelerate the oxidation of pollutants. VOCs and other pollutants are converted into CO₂ and H₂O. As the temperatures of the exhaust air during the roasting process are often not sufficient to ensure that the catalyst functions properly, the exhaust air must be heated in some applications.
- Advantages: Significantly lower energy consumption compared to thermal post-combustion, as the reaction can take place at lower temperatures due to the catalyst.
- Efficiency: Particularly effective in reducing carbon monoxide, formaldehyde, VOCs and odors. NOx emissions can also be reduced.
