Method for production of sulfuric acid from sulfur containing feeds with gas quenching

A method for the production of sulfur trioxide from a feed stream comprising sulfur-containing compounds and dissolved metals and alkali metals, said process comprising the following steps:

• incineration in the presence of an O2-rich stream and optionally a support fuel, whereby the sulfur-containing compounds in the feed stream are converted to SO2 and the dissolved metals and alkali metals are converted into a partly solidified dust,
• mixing the hot process gas from the incinerator with a stream of colder gas in a mixing unit, such that the temperature of the combined stream is below the particle solidification temperature,
• cooling of the combined gas stream in one or two heat exchangers,
• removing solid dust particles from the combined gas stream in a dust removal device,
• optionally adding hot dilution air to the process gas to provide sufficient oxygen for the oxidation of SO2 to SO3 in an SO2 converter, and
• feeding the process gas to an SO2 converter consisting of a number of catalyst layers with heat exchangers installed between the catalyst layers, thereby converting the SO2 in the process gas to SO3.