亁底渣從爐膛掉到輸送系統再回送到爐膛再燃燒之後，由空氣冷卻。再燃燒及底灰冷卻的過程，會回收可用的熱能(Dry bottom ash handling: dry hot bottom ash falls from the furnace onto a mechanical conveyor system and, after redirection to the furnace for reburning, is cooled down by ambient air. Useful energy is recovered from both the ash reburning and ash cooling)
