MULTIPLE HEARTH FURNACE

摘要

A multiple hearth furnace comprises a gas cooling system for its central shaft (20) and its rabble arms (26). This gas cooling system includes within the shaft (20) an annular main distribution channel (54, 54') for supplying a cooling gas to the rabble arms (26) and a central exhaust channel (56) for evacuating the cooling gas leaving said rabble arms (26). The gas cooling system further comprises an annular main supply channel (52, 52') surrounding the annular main distribution channel (54, 54') and being outwardly delimited by an outer shell (50) of the shaft. A cooling gas inlet (44', 44") is connected to the annular main supply channel (52, 52'). A cooling gas passage (60', 60"') between the annular main supply channel (52, 52') and the annular main distribution channel (54, 54') is spaced from the cooling gas inlet (44', 44"), so that cooling gas supplied to the cooling gas inlet (44', 44") has to flow through the annular main supply channel (52, 52') through several hearth chambers (12) before it flows through the cooling gas passage (60', 60") into the annular main distribution channel (54, 54').