The subject of this Concept is sulphur fuelled hybrid energy system envisioned as a semi-cycle where CO2 is catalytically activated/converted at moderate temperatures to form intermediate sulphur compound carbonyl sulphide (COS) that subsequently reduces product of sulphur combustion, sulphur dioxide (SO2), to yield carbon dioxide in a form that can readily be captured, and to forming sulphur in a potentially 100% conversion process. The sulphur fuel comprises a gaseous mixture of sulphur vapour (Sn) and sulphur dioxide provided by bubbling oxygen through molten sulphur, industrial proven method called submerged combustion. Furthermore, the system taking advantage of the submerged combustor for the chemical reduction of the sulphur trioxide (SO3) to SO2 in the bed of molten sulphur. In result of that the accompanying the system sulphur thermochemical water-splitting process can efficiently generate hydrogen at significantly lower temperatures (H2SO4 decomposition at ≅400°C.) then current art which carried out the SO2 recovery at temperatures above 800° C., in order to produce a sensible equilibrium conversion.
To overcome the temperature and pressure limitations associated with refractory linings, the water-wall boiler is employed designed with a radiant section, using water-wall tubes, capable of withstanding a very high gas temperature. The theoretical temperature of adiabatic burning of sulphur vapour in oxygen taking in to consideration dissociation process is about 3000-3500°C. Though, burning diatomic sulphur (S2) in pure oxygen in stoichiometric quantities would produce an even higher temperature - more than 5,000°C!
The homogeneous gas-phase reaction between COS and SO2 in a range of temperature of 700-2000K, pressure of 1-35 atm, and COS:SO2 ratio of 0.6:1 to 2.4:1 is extremely rapid and do not merely yield sulfur and CO2 but a significant amount of CO as well. Therefore, sufficient furnace volume is provided for the cooling of the reaction product to be favourable thermodynamically for re-association of CO and sulphur to yield COS.
Every element in this proposed system has passed beyond the laboratory bench; most are already implemented somewhere at demonstration and/or full industrial scale. Application of this concept for auxiliary power generation is virtually universal and a wide variety of arrangements or modifications to the proposed system are possible.