Process for producing sulfur

The invention relates to a process device, which comprises the following steps: comprises a Claus reaction furnace, a Claus waste heat boiler and SO₃A decomposition section and a Claus conversion section, wherein the Claus reaction furnace has an inlet and an outlet, the Claus waste heat boiler has a gas inlet, a gas outlet and optionally an elemental sulphur outlet, SO₃The decomposition section has a gas inlet and a gas outlet, and the Claus conversion section has a gas inlet and a gas outletA port and an elemental sulfur outlet, and wherein the inlet of the claus reaction furnace is configured for receiving the feed gas, sulfuric acid, fuel, oxidant, and optionally a sulfuric acid atomizing medium, and the outlet of the claus reaction furnace is configured in fluid communication with the inlet of the claus waste heat boiler, wherein the outlet of the claus waste heat boiler is configured to be in fluid communication with the SO outlet₃The inlet of the decomposition section is in fluid communication with SO₃The outlet of the decomposition section is in fluid communication with the inlet of the claus conversion section. The process has the associated benefit that it avoids undesirable poisoning of the claus catalyst (sulfation) and contamination of the elemental sulphur product with sulphuric acid in the claus conversion stage.