(182g) Hybrid Sulfur Cycle Flowsheets for Hydrogen Production from Nuclear Energy

Conceptual designs for two versions of a Hybrid Sulfur (HyS) process for the centralized production of hydrogen (H2) using an advanced nuclear reactor heat source have been developed and economic analyses carried out. Both flowsheets are based on Proton Exchange Membrane (PEM) electrolyzer technology. One electrolyzer uses sulfur dioxide (SO2) dissolved in concentrated sulfuric acid as the anolyte and has an H2 vapor cathode. In this device, SO2 is oxidized with water at the anode to produce H2SO4, while the protons also formed are transported across the PEM and reduced at the cathode to H2. The other electrolyzer has a pure water catholyte and an anhydrous SO2 vapor anode. Here, SO2 is oxidized with water that diffuses across the membrane into the porous anode to make H2SO4. Concentrated sulfuric acid forms at the anode as a liquid product, while protons are transported across the PEM to make H2 at the cathode that can be easily separated from the water catholyte. The flowsheets were modeled, using Aspen Plus?, and material and energy balances were prepared from the simulation results. The presentation will describe these flowsheets, including unit operations and operating conditions, provide thermal efficiency estimates, and give an estimate of H2 production costs.