Economiser
An economiser is a heat exchanger that recovers heat from boiler flue gas to preheat the feedwater. It is one of the most common, low-risk boiler efficiency retrofits, cutting the fuel needed to raise feedwater to steam temperature.
By capturing heat that would otherwise leave up the stack, an economiser lowers flue-gas temperature and raises overall boiler efficiency by several points. Condensing economisers go further, recovering latent heat from water vapour in the flue gas where the duty allows. It is a staple of waste-heat recovery on steam plant.
Related terms
Waste Heat Recovery · Boiler Blowdown · Superheat
Related guides
How to improve boiler efficiency
The practical levers that move boiler efficiency — combustion, blowdown, feedwater, flue-gas heat and standing losses — and how to find them.
Waste heat recovery in industry
Where industrial waste heat hides, the technologies that capture it, and how to judge whether recovery pays at your site.
Where this applies
Retrofitting waste-heat recovery · Retrofitting a boiler economiser · Controlling air preheater leakage · Cleaning a feedwater economiser