Heat recovery at low flue gas temperatures

Where are condensers applied?

Condensers are often used in steam boilers and dryers, sometimes in combination with an upstream economiser. This type of heat exchanger uses phase transition to extract energy from low temperatures. The output is very suitable for low-temperature consumers.

The operating principle of a condenser

A condenser is usually made of stainless steel tubes. (Flue) gas flows around the tube, at a higher temperature than the wall of the tube. As a result, the gas will release its heat through the wall to the cold water in the pipe, creating condensate (water) on the flue gas side. A condenser can therefore recover not only the tangible heat but also the latent heat (heat released during condensation) from the flue gases, thereby improving the efficiency. The heat recovered from the condenser can then be reused in business processes.

Benefits and gains

• You recover a substantial amount of energy at a relatively low temperature. (The water dew point of most gaseous streams is between 40 and 70⁰C).
• The condensation energy in a drying air stream is approximately equal to the evaporation energy fed into the dryer. Applying a condenser thus leads to an energy efficiency improvement and lowers your CO₂ emissions. 

Condenser models

Condensers can be built in various configurations

ONTWERPKEUZE

What design is the best match for you?

Depending on the application, a specific design is needed. Condensers come into contact with moisture or water, which can cause corrosion. Corrosion can also result from low pH values due to acids present in the flue gas. Corrosion-resistant materials are therefore necessary in almost all condensers for proper operation.

Your flue gas or drying air is clean

If the drying air or flue gas is (virtually) free of dust particles, a compact condenser design is sufficient. In this case, the condenser is made of stainless steel.  

Your flue gas is corrosive

Due to the phase transition in a condenser, liquid water is present by definition. This is why a condenser is usually made of stainless steel. Corrosive components in the drying air or in the flue gas determine what type of stainless steel should be used. Sometimes, plastic cladding is required.

Your flue gas, baking fumes or drying air is contaminated

If the flue gas is contaminated, a cleaning system may be necessary. Sometimes, self-cleaning can be used instead. When the flue gas flows vertically through the condenser, we can ensure that the condensate has a self-cleaning effect on the pipes. The condensate is separated from the cooled gas through the lower section of the condenser and discharged.