Liquid sulfur is precisely metered and fed to the sulfur burner, where it fully combusts with dry air to generate SO₂. After cooling, the SO₂ gas enters the converter and is converted to SO₃ over a vanadium catalyst. Following further cooling, the SO₃ gas is sent to the sulphonation/sulfation unit. The SO₂ and SO₃ gases are cooled by cooling air in a tube-type heat exchanger; the resulting hot air is collected and routed to the waste heat recovery unit to generate steam and hot water. The secondary hot air is then used for silica gel regeneration and for the evaporation and crystallization of scrubber wastewater in Unit 38.   Features: The SO₂ cooler adopts inlet-end insulation protection and a floating-tube design, which prevents intergranular corrosion of the stainless steel above 600 °C and doubles the service life. By integrating the start-up pre-heater with the waste heat recovery unit, the steam produced during converter preheating is also used for sulfur melting and hot-water generation, so that WEIXIAN plants require no external steam.