The Formation of Bonded Fireside Deposits in Pulverized-coal-fired Boilers of Thermal Power Station (II)

Abstract

The fireside deposits of furnace tubes in pulverized-coal-fired boilers installed in thermal power stations are classified, as previously reported, into the three main groups fly ash, sliiceous slag and ferruginous slag. Although, “the most inner layer” of these deposits, so named provisionally by us, bonded directly on the tube have not been studied in detail of its characters or origin.
Continuted studies of these deposits have developed additional data of the inner layer concerning its chemical composition and X-ray diffractive analyses. Consequently, the layer with 2 mm in average thickness shows a marked differences by an excessive concentration of SO₃ (about 35%) and is composed mainly of complex iron and or aluminum alkali sulfates. Jhus, the layer has been comcluded to be called the “sulfateous slag, ” which is formed on the first stage of fireside depositions. Further, the reaction of its slag with tube metal and its influence on the formation of other slags are discussed here.