Process for the production of sulfuric acid

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 conversion step in which SO₂ is oxidized to SO₃ over one or more catalyst beds, (b) cooling the SO₃-containing gas from said first contacting step by passing said gas to an intermediate condensing stage withdrawing a gas containing unconverted SO₂ and unabsorbed SO₃ and withdrawing a product stream of concentrated sulfuric acid, (c) reheating said gas containing unconverted SO₂ and unabsorbed SO₃, (d) passing the gas from step (c) to a second catalytic conversion 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 100° 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 assumption 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 with 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 under the assumption that SO₃ is not hydrated to H₂SO₄, (h) withdrawing from the final wet condensing stage of step (f) a stream of 70-98 wt % sulfuric acid.