| 摘要 |
1500096 Two stage fluidized treatment METALLGES AG 14 May 1976 [3 June 1975]20118/76 Heading C1A [Also in Division B1] Endothermic processes, other than the decomposition of aluminium chloride hydrate to yield Al 2 O 3 , are carried out by introducing a solid material entrained in a gas stream into a fluidized bed reactor 1 to produce an expanded fluidized bed in which the solids concentration decreases from bottom to the top of reactor and wherein fluidizing or primary air is supplied to the fluidized bed reactor through a gas distributer, separating the solids from the gas and in which the separated solid material and secondary air are fed into the reactor at points 3 and 4, respectively above the gas distributer used for admitting the fluidizing air (2) and the heat of reaction being produced by combustion of fuel, the fuel being fed 5 into the zone between the gas distributer and secondary air inlet, and in which the solids, entrained by gases exhausting at the top of the reactor, are separated therefrom and fed into a holding reactor 6 in which they are fluidized, a partial stream of solids from 6 being recycled to the fluidized-bed reactor to maintain a predetermined solids content of suspension therein. Preferably, the density of the suspension in the fluidized bed reactor is controlled to correspond to a solids volume of 2 to 20% of the reactor volume between the gas distributer and the secondary air inlet and to a solids volume of 0À2 to 2% of the reactor volume above the secondary air inlet. The solids content in the holding reactor may be controlled to 35% of the volume of the holding reactor. Residence times in the holding reactor are typically 2-10 times those in the fluidized bed reactor-the latter being 10 to 30 mins. in duration. A fluidized bed cooler may be used to cool the stream of solids emerging from the holding reactor, the extracted heat being used to heat the secondary air or the fluidizing air. The present method is particularly useful for drying crystalline inorganic compounds (e.g. the hydroxides of Mg, Fe or Al), the burning of lime and dolomite, the deacidification of cement, or the decomposition of FeSO 4 or MgSO 4 and high-temperature metallurgical processes (e.g. the oxidation of ilmenite). |
