Simulation and thermodynamic analysis of chemical looping reforming and CO2 enhanced chemical looping reforming

The production of hydrogen from methane via two chemical looping reforming (CLR) processes was simulated and thermodynamically analysed, one process being the conventional CLR process, the other being a CO₂ sorption enhanced process. The aim of the work was to identify suitable operating conditions for obtaining an optimum hydrogen gas purity and yield, whilst operating auto-thermally, at atmospheric pressure and with no carbon formation. In both simulations, the reactors were simulated using the Gibbs minimisation technique. NiO was used as the oxygen storing species, whilst CaO was used as the CO₂ adsorbent.     

Simulation of flow and drying characteristics of high-moisture particles in an impinging stream dryer via CFD-DEM

Impinging stream dryer (ISD) is an alternative for drying high-moisture particulate materials. Due to the complex multiphase transport phenomena that take place within an ISD, use of a reliable computational model instead of a tedious experimental route to aid the design of the dryer is desirable. In the present study, computational fluid dynamics were used in combination with the discrete element method (CFD-DEM) to predict, for the first time, the multiphase transport phenomena within a coaxial ISD; results from a model that does not consider particle-particle interactions (CFD) were also obtained and compared with those from the CFD-DEM model. In all cases, high-moisture particles having negligible internal transport resistance were assumed. Both models were used to simulate the gas-particle motion behavior, particle mean moisture content, particle mean residence time, and particle residence time distribution. The simulated results from both models were compared with the experimental data whenever possible. The results showed that the CFD-DEM model could be utilized to predict the particle motion behavior and led to more physically realistic results than the CFD model. The CFD-DEM model also gave predictions that were in better agreement with the experimental mean particle residence time and moisture content data.