GB1120232A - Process for producing sulphur trioxide and/or sulphur acid from gases which contain sulphur dioxide by the catalytic oxidation of the sulphur dioxide - Google Patents

Abstract

<PICT:1120232/C1/1> A process for the catalytic conversion of SO2-containing gases having an SO2 content of from 8 to 11% by volume to form SO3 and/or sulphuric acid, comprises subjecting the gases to catalytic conversion in the first stage of a two-stage catalytic converter, each stage of which comprises two contact hurdles, to effect a conversion of 70 to 90% by volume of the total SO2 contained in the starting gases, cooling the gases, effecting an intermediate absorption of the SO3 formed in the first converter stage, and contained the cooled gases, heating the gases to the temperature required for conversion in the second converter stage, subjecting the gases to conversion of the first hurdle of the second converter stage, cooling the gases from the first contact hurdle of the second converter stage to the working temperature of the second contact hurdle, subjecting the gases to conversion over the second contact hurdle of the second converter stage, cooling the gases from the second contact hurdle of the second converter stage, and absorbing the SO3 formed in the second conversion stage. In an embodiment, the gas produced in sulphur combustion chamber 1 of 10% by volume SO2 content passes through 2 into waste heat boiler 3. The cooled gas is fed through 4 into first contact hurdle 5 of catalytic converter 6 and leaves through 7 before mixing with cold dried air entering chamber 8 through 9. The gas flows to a heat exchanger 11 through 10 and is cooled with cold air fed from blower 12 through 13. The air is discharged from 11 through conduit 14 and through 15 into the second contact hurdle 16. After conversion of 85% the gas passes to heat exchanger 18 and steam generator or water preheater 19 and then through 20 to absorber 21. The SO3-freed gases leave 21 through conduit 22, are heated in heat exchanger 18 and pass to third contact hurdle 24 by way of conduit 23. The gases then enter heat exchanger 26 through conduit 25 and are cooled with cold air supplied through conduit 27 and discharged through 28. The cooled gases pass through 29 to the last contact hurdle. The completely catalysed gases leave through 31 to steam generator or feed water preheater 32 before passing by way of 33 to final absorber 34 before discharge through 35. The feed water preheater 19 and/or 32 may be associated with waste heat boiler 3. Cold air from conduit 14 is combined with that from conduit 28 and flows through 36 to combustion chamber 1.