| 摘要 |
<p>In the first stage, much of the sulphur dioxide is oxidised catalytically, with addn. of oxygen, to sulphur trioxide, which is sepd. from the unreacted sulphur dioxide. Then the sulphur dioxide in the exit gas from the first stage is oxidised catalytically, with addn. of oxygen and sufficient air to give an exit gas with the compsn., after sepn. of much of the sulphur dioxide, of a partially catalytically oxidised gas, w.r.t. SO3, SO2 and O2 content, as obtd. in a S combustion gas with the usual sulphur dioxide concn. In the third stage, the exit gas from the second stage is processed to sulphuric acid in the conventional manner. The process can be carried out with relatively small and therefore cheaper plant, since the total vol. of the gas is reduced by the absence of inert gases. The addn. of air in the second stage prevents waste of costly pure oxygen. In an example the process was carried out as described, using 4- part first and second stages. The overall conversion was 99.98%. The output from the individual plants was 900, 250 and 10 t/day, cf. 250, 12 and 10 t/day if the same plants were used conventionally.</p> |
