| 摘要 |
Process of producing sulfuric acid from feed gases containing 0.1-30% SO2 comprising the steps of : (a) passing the feed gas to a first catalytic con version step in which SO2 is oxidized to SO3 over one or more catalyst beds, (b) cooling the S03-containing gas from said first contacting step by passi ng said gas to an intermediate condensing stage withdrawing a gas containing unconverted SO2 and unabsorbed SO3 and withdrawing a product stream of conc entrated sulfuric acid, (c) reheating said gas containing unconverted SO2 an d unabsorbed SO3, (d) passing the gas from step (c) to a second catalytic co nversion step, in which unconverted SO2 is oxidized to SO3 over one or more catalyst beds, (e) cooling the gas from step (d) to a temperature of 0 to 10 0 °C above the acid dew point of said gas, (f) passing the gas from step (e) with a molar ratio of H2O to SO3 of at least 1.05 calculated under the assu mption that SO3 is not hydrated to H2SO4, and acid dew point of below about 240 °C to a final wet condensing stage, in which the remaining sulfuric acid is condensed by cooling of said gas by indirect or direct heat exchange wit h a cooling medium, (g) providing in the gas, prior to conducting step (f), a content of 1010 to 1013 solid particles per Nm3 per vol% SO3 calculated un der the assumption that SO3 is not hydrated toH2SO4, (h) withdrawing from th e final wet condensing stage of step (f) a stream of 70-98 wt% sulfuric acid .
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