Recuperators and regenerators
Using hot exhaust to preheat combustion air in furnaces, kilns and glass melting.
Recovery and reuse · Heat to heat · No. 121
- Recovery and reuse
- Heat grade: High (above 650 C)
Feed a furnace's own 1,200 C exhaust back into its burners and it can save up to half its fuel.
Chart: Illustration: Recuperators and regenerators
Where it comes from
Chart: Map of where it comes from
Recuperators and regenerators take heat from furnace exhaust and hand it straight back to the incoming air. Glass furnace exhaust leaves at 1,300 to 1,540 C, the hottest waste heat in industry.
Three things to know
- A 1,315 C gas furnace fed with 870 C air burns 51% less fuel than one with cold air.
- Ordinary metals give up above about 870 to 1,090 C, so the hottest exhausts need ceramic tubes or refractory brick.
- Ljungstrom rotary air heaters had saved fuel equal to about 4.5 billion tonnes of oil by 1995, on an ASME estimate.
The journey
- 1 Hot exhaustFurnace gas leaves at over 1,000 C
- 2 ExchangerRecuperator tubes or brick regenerator checkers
- 3 Hot airCombustion air preheated to about 1,000 C
- 4 BurnerHot air means less fuel per flame
- 5 Furnace outputGlass, steel, aluminium and ceramics