Thermal reduction of sulfur dioxide to sulfur with temperature controlled furnace

Abstract

Processes for the thermal reduction of sulfur dioxide to elemental sulfur are disclosed. The processes described include three general reaction sections, including the reaction furnace portion where the SO2-containing stream is combusted, the second reaction zone where the temperature is moderated to encourage the reaction of sulfur with hydrogen to consume the hydrogen carbon monoxide and produce the H2S and CO. The temperature moderation is achieved by one or combinations of three different methods adding external waste heat boiler, followed by a vessel to provide adequate residence time for the reaction of producing H2S or to recycle the tail gas to a second zone of a 2-zone reaction furnace, using inter-stage internal cooling coil or adding a quench fluid in the second zone of a 2-zone reaction furnace. The third reaction zone is a Claus conversion portion, wherein residual H2S and SO2 are further reacted to produce additional elemental sulfur.

Dependencies are inferred from the claim text.