In accordance with local regulations
All systems are equipped in the first stage with a multi-cyclone filter to remove dust. In the second stage the flue gas cleaning takes place. The applied flue gas cleaning technique is strongly dependent on the type of fuel and local emission regulations. The emission requirements often determine the type of filtering system.
A flue gas condenser is applied when the dust emission requirement is lower than 100mg/Nm3 and with clean fuels. An electrostatic filter is applied till 20 mg/Nm3. A bag house filter is applied where stricter requirements need to be met.
An absorbent-injection is applied where chloride, sulphur or other chemical contaminations need to be removed. An absorbent-injection is always equipped in combination with a bag house filter. The absorbent, bicarbonate or lime, is selected based on the desired cleaning temperatures and concentrations of the chemicals. Active carbon can also be dosed if required.
Low NOx emissions
A special combustion technique is applied in a HoSt installation that keeps NOx emissions relatively low. However, if NOx emissions are high, should there be high nitrogen concentrations in the fuel or if local emission requirements are strict, then we can provide additional measures as needed.
Urea-injection in the furnace can be applied to reduce the NOx emission down to approximately 50%. If an even lower NOx emission is required then a de-NOx system is installed downstream to further reduce NOx concentrations.