Verfahren zur Herstellung von Schwefeltrioxid

1316608 Multistage SO 3 contact process BAYER AG 22 May 1970 [10 June 1969] 24894/70 Heading ClA SO 3 is produced from SO 2 -containing gases introduced at a temperature up to 300‹ C. into a first catalyst stage, containing a bed of catalyst fluidized thereby, where at least 60% of the SO 2 is converted, the gas then passes to an intermediate absorption stage, and then to another catalyst stage which may be either a fixed bed or a fluidized bed. The first catalyst stage may comprise two steps, the second of which may be either fluidized or fixed bed. Catalyst may be carried from the first to the second step with the gas, and this may be compensated for by a separator which separates catalyst and directs it to the first reactor. Several embodiments are shown, in one of which (Fig. 5), the waste gases from pyrites roasting are introduced through heat exchanger la into fluidized reactor 2, through fixed bed reactors in the upper part of four-stage reactor 12 and thence to the remaining two fixed beds via heat exchanger 4 and absorber 5. Cooling means 1b and 11 is provided between the respective pairs of fixed beds and after passage through heat exchanger la, the effluent from the last bed passes to final absorber 7.