Adiabatic UT-3 thermochemical process for hydrogen production

Abstract The UT-3 thermochemical hydrogen producing cycle is a four step process developed at the University of Tokyo. In the process, only solid and gas reactants/products are used and the maximum temperature is 1033 K. In this paper, a new UT-3 process has been developed in which all four reactions are carried out adiabatically using a heat carrier vector (steam or an inert gas). The new process has been evaluated using the ASPEN-PLUS process code. The first law efficiency of the cycle has been determined as 48.9% and the second law efficiency as 53.2%. The process can be realized using conventional materials for the reactors, which can be packed bed, honeycomb or fluidized bed type. In the latter case, it is found that the flow rate of the heat carrier fluid is sufficient to fluidize all four reactors. For a plant producing 30,000 Nm3 per hour or 2.68 × 106 GJ H2 per year, the plant sizing has been carried out, its operation is discussed and its advantages are presented.