ZANNI - Filter Systems

• There are two ways to filter the exhaust gas.
• On the one hand there is the wet and dry washing technology and on the other hand the electrostatic filter technology.
• For our systems we mainly use the dry washing technology.
• For our dry washing technology we can offer ceramic filters and fabric filters.
• We prefer ceramic filters for the most of our furnaces, as these have a very high filter efficiency on the one hand and a very long service life on the other.
• Which of these both filter technologies is suitable is mainly a question of the amount of exhaust gas and the media itself.

Dry-washing systems

• Dry scrubbing systems are used to remove corrosive and toxic gases (for example SO2 and HCl) from the exhaust gas.
• They are very effective with low investment and operating costs.
• The temperature range for the dry-scrubbing solvent should be from 170°C up to 300°C.
• In this range the dry-scrubbing solvent can transfer the contents.
• Flue gas mixed with dry-scrubbing solvent create a layer on outside surface of the filter and accumulate during operation.
• The dust layer causes a pressure drop and a differential pressure measurement indicate necessary cleaning steps.
• At a certain differential pressure level the filter will be cleaned by pressure air with a reverse jet cleaning system which clean the filter by a jet impulse and the dust layer on the outside surface of the filter will fall down.
• At the bottom of the filter the ash feed by a rotary valve to a big bag or ash container.

Optional protective equipment against corrosion during plant shutdowns

• The insulation at the outside of filter body keeps it from corrosion, during shut down periods.
• The dust inside is contaminated with sulpher and other components.
• If the temperature falls below the dew point, corrosion could be happen.
• Therfor a standstill heater is additionally recommended to protect the housing from corrosion.
• This heater is only an option, because if it is necessary depends allways only on local conditions.

Easy replacement of the filter cartridges

• The filter can easily removed when necessary.
• It can be replaced by operation staff after training.