Heat and plume lost up the stack
Conventional boilers expel flue gas well above ambient temperature, wasting sensible heat, and the warm, moisture-laden plume can condense into a visible white plume that annoys neighbors. Recovering that heat for incoming combustion air or building heating cuts fuel use and can suppress the plume.
Suitable exchanger types and how they work
A stainless plate air preheater transfers flue-gas heat to the combustion air or a separate heating loop. Running the exhaust below its dew point lets a condensing exchanger also recover latent heat, squeezing more efficiency out of the same fuel. An air-to-water recovery loop is an alternative when water heating is the better sink.
Design considerations for flue gas
Flue gas is corrosive, especially below the acid dew point. Specify stainless or alloy plates, provide condensate collection and neutralization, and protect against low-temperature corrosion. Size for the boiler’s flue volume and pressure drop, and ensure the recovered heat has a real use (preheat, space heating, or process) so the savings are captured.
Typical Application Environments
Heat recovery is valuable wherever a building or process expels warm, stale air while drawing in cold or hot fresh air. Common sites include factory make-up air systems, commercial kitchens, paint booths, drying rooms, laboratories, and cleanrooms. In each case the exhausted air still holds usable thermal energy, and capturing it reduces the heating or cooling demand placed on the primary plant.
Matching the Unit to the Duty
The right selection starts with the air volume, the temperature difference between streams, and the cleanliness of the exhaust. Clean, steady flows suit plate exchangers; humid or dusty exhaust may need a rotary wheel with purge or a unit arranged for easy wash-down. Pressure drop must stay within the fan curve, and the core material must resist any contaminants present in the airstream.
Integration Tips
For the Boiler Flue Gas Heat Recovery and Plume Abatement duty, position the exchanger so the exhaust is filtered before it reaches the core, and provide condensate drainage where the supply side may drop below the dew point. Balanced supply and exhaust fans keep the building neutral in pressure, which protects indoor air quality and process control. A bypass damper lets the system free-cool in mild weather.
Frequently Asked Questions
Can it handle greasy kitchen air? Yes, with a rotary wheel and a wash cycle, though the exhaust should first pass a grease filter. Will it cause condensation? Some condensate is normal in winter; provide a drain or a defrost strategy on the supply side.
