Effects of Raschig Ring Packing Patterns on Pressure Drop, Heat Transfer, Methane Conversion, and Coke Deposition on a Semi-pilot-scale Packed Bed Reformer

The effects of Raschig ring packing patterns on the efficiency of dry methane reforming reactions were investigated using computational fluid dynamics (CFD). The present study aims to understand the behavior of fluid flow in packed bed reactors, especially under low reactor-to-ring ratios between 4 and 8. Three packing patterns were studied: vertical staggered (VS), chessboard staggered (CS), and reciprocal staggered (RS). It was determined that packing pattern notably affected pressure drop across the reactor length. The VS pattern produced the lowest pressure drop of 223 mPa, while the CS and RS patterns produced pressure drops of 228 mPa and 308 mPa, respectively. The values of methane conversion can be increased by ca. 2 % by selecting a more suitable packing pattern (i.e., 76 % for the VS pattern and 74 % for the CS and RS patterns). This work is licensed under a Creative Commons Attribution 4.0 International License

Optimisation of a sorption-enhanced chemical looping steam methane reforming process

An intensified hydrogen production steam reforming process named ‘Sorption-Enhanced Chemical Looping Steam Methane Reforming’ (SE-CL-SMR) was studied. Aspen Plus was used to carry out a thermodynamic investigation into the influence of various operating conditions on hydrogen production and process thermal efficiency. The steam to carbon molar ratio (S/C), the CaO to carbon molar ratio (CaO/C), the metal oxide to carbon molar ratio (MeO/C), the metal oxide composition (NiO:CuO), and the oxidising agent species were all shown to influence the process performance. The main findings were that; (1) the introduction of CaO reduces the potential for coke formation with predicted zero coke formation for CaO/C ratios > 0.4; (2) increasing amounts of metal oxide (MeO/C) and steam (S/C) enhance the hydrogen production yield and purity; (3) due to its involvement in an exothermic reaction, the presence of CuO allows for the reforming reactor to operate as an adiabatic reactor with an operating temperature within the range of 600 °C–700 °C; (4) an increase in the NiO:CuO ratio leads to an increase in methane conversion. With the operating conditions of S/C = 3, CaO/C = 1, MeO/C = 1, NiO:CuO = 0.9 and air as the oxidising agent, a hydrogen purity as high as 98% was predicted for the SE-CL-SMR process, along with the lowest observed CO2 production rate. Under the same conditions and using pinch analysis, the thermodynamic model prediction of the thermal process efficiency is reported as ca. 86%. This is significantly higher than the reported efficiency of 79% for the ‘Sorption-Enhanced Steam Methane Reforming’ (SE-SMR) process, predicted using similar thermodynamic models