Sulphuric acid production via Chemical Looping Combustion of elemental sulphur

Abstract

A relevant objective of the sulphuric acid (H2SO4) production industry today is to obtain sulphur dioxide (SO2) gas streams with the highest possible SO2 concentration after the elemental sulphur combustion stage in order to reduce both capital and operating costs. A new technology, Chemical Looping Combustion (CLC), is able to generate gaseous streams that are highly concentrated in combustion products by means of oxygen transfer from air to the fuel using a solid oxygen carrier. This work proposes a new process for H2SO4 production via CLC and using elemental sulphur as fuel. An oxygen carrier with high sulphur resistance should be used for this purpose. The analysis of this process has brought promising results, such as the easy integration of the CLC system into the entire H2SO4 production plant and the confirmation that this is a process in which the energy potential of sulphur is exploited to a very high degree. Furthermore, the proof of concept was carried out by burning elemental sulphur in a 500Wth CLC unit with a high sulphur-resistant oxygen carrier based on iron oxide, Fe20γAl. This work presents the first ever results of elemental sulphur combustion by an oxygen carrier. Complete combustion of sulphur to SO2 was achieved, and no deactivation of the oxygen carrier was observed. Considering all the results obtained in this work, it can be concluded that the production of H2SO4 via CLC is a feasible technology which can provide a series of relevant techno-economic benefits in comparison with current industrial production process.