(328e) Design of Recuperative Sulfuric Acid Decomposition Reactor for Hydrogen Generation Processes

The Hybrid Sulfur Process (HyS), as well as similar sulfur cycles for the production of nuclear hydrogen, requires the decomposition of sulfuric acid into sulfur dioxide, oxygen, and water at temperatures above 800°C and a pressure near 9 MPa. The design of a reactor for this process presents numerous challenges in terms of maintaining small pressure differentials and utilizing currently available materials of construction. This paper focuses on design calculations for a recuperative decomposition reactor for use in the production of hydrogen. The decomposition reaction takes place within individual tubes of a multi-tube reactor that are is fed 50 wt% H2SO4 at 50 to150°C.

Previous calculations involved modeling to produce a detailed temperature-enthalpy (T-H) diagram for the H2SO4-SO3-SO2-O2-H2O system of the evaporation and decomposition processes for pinch analysis. Previous detailed modeling and analysis has been performed for the Westinghouse design by Connolly, et al(2). Current analysis involves detailed modeling and sizing of the recuperative concept. This design phase entailed detailed heat transfer analysis and sizing of the reactor. Calculations were performed with a multi-tube reactor design in which the outer shell of the reactor contained structured packing to facilitate heat transfer on the shell side. This resulted in a design consisting of a total of 750 tubes at 6.7 meters in length contained in two vessels with an inner diameter of 3.7 meters.