(550e) Numerical Study of Hydrogen Production Via High-Temperature and Low-Temperature Water-Gas Shift Reactors’ System: The Multi-Scale (Pellet-Reactor Scale) Modeling Approach and Simulation

Authors: 
Karagoz, S., UCLA
da Cruz, F., University of California, Los Angeles
Manousiouthakis, V., University of California Los Angeles, Los Angeles
The primary objective of this work is to develop an advanced, and detailed mathematical model of a packed bed reactors (PBRs) carrying out high-temperature and low-temperature water gas shift reactions (WGSRs) for the hydrogen production. In industry, the water gas shift reactors consist of two different temperature stages, the high-temperature shift reactor (HTSR) and the low-temperature shift reactor (LTSR) with a cooling process between them is a recommended for the operation of hydrogen generation. Therefore, detailed and advanced numerical simulations on the HTSR and the LTSR in series are performed to predict the behavior of hydrogen production system. After completing a single-pellet, non-isothermal, steady-state simulation, we couple our model with a non-isothermal (adiabatic), steady-state packed-bed reactor model to form a hybrid multi-scale reactor model. The velocity, temperature and species’ concentration profiles along both the reactor length and the pellet radius are captured by using rigorously defined momentum, energy, and species transport models, accounting for the physical mechanisms involved in the system such as convection, conduction, and reaction-diffusion. This effort provides a detailed numerical insight into the transport phenomena with multiscale studies in porous media (pellet and reactor scales). The rigorous Maxwell-Stefan Model is applied on the reactor scale to account mass diffusion fluxes. On the other hand, Dusty Gas Model is considered to describe mass diffusion fluxes for the single pellet scale. Studies that include a broad range of the operating conditions and parameters (e.g. reactor temperature, reactor size (weight of catalyst), the inlet gas composition, and the inlet gas flow rate) are carried out in this paper, in order to investigate the upper and lower limit conditions’ effects on the results.