Flue gas condensation


Flue gas condensation is a proven process for maximizing energy output from damp or hydrogen-rich fuels. By burning of biomass, peat, waste or natural gas, flue gas contains a high proportion of water vapor. Water vapor condenses through cooling of flue gas with the return of district heat. The heat energy released during flue gas condensation is thereby transferred to the district heating water. The flue gas leaves the condenser at a temperature which is only a few degrees above the incoming district heating temperature. The condenser consists of a lamella heat exchanger of EnviBAT’s own design. The lamella heat exchanger is characterized by:

•  Efficient heat transfer

•  Low pressure drops at both flue gas and district heating side

•  Compact layout

•  High corrosion resistance

•  Provides typically return 15-25% of the boiler output


The flue gas condensation formed in the condenser is led to the water treatment before it is discharged to the sewer or receiving water. Water treatment is designed to meet set conditions and environmental requirements.

Air moistening

To provide additional flue gas cooling, air moistening can be used. The humidifier is a lamella heat exchanger of the same design as the condenser, thus have the same benefits described here before. In the humidifier flue gas heat is exchanged against the incoming combustion air. Thermal energy and moisture are transferred from the flue gas to the air. The air is passed to the boiler and is much more energetic because of the humidification process, which means that flue gas is more energetic and more energy can be recovered in the condenser.


  • Recovers typically equivalent to 25-30% of the boiler output
  • Has the potential in some cases to recover up to 35%