Chemical looping reforming of bioethanol for hydrogen production: Modeling and design of the fuel reactor of a 350 MW unit

Abstract

Chemical Looping Reforming of bioethanol offers an efficient process for the production of high-quality syngas which may be easily integrated with CO₂ capture technologies for the H₂ production with negative CO₂ emissions. In this work, the fuel reactor of a 350 MW Chemical Looping Reforming unit, fed with raw ethanol obtained after the first distillation, has been modeled. A macroscopic model was developed by integrating the fluid dynamics of a high-velocity fluidized bed with the kinetics of catalytic ethanol conversion. The Ni-based oxygen carrier exhibited sufficient catalytic activity and oxygen transport capacity to fully convert ethanol, with CO and H₂ as the main gas products. Simulation work was done to evaluate the syngas production as a function of the operating conditions. Eventually, the basic parameters for the design of the fuel reactor are defined. Results from mass and enthalpy balances indicated that suitable conditions to maximize syngas yield (4.3 mol H₂ per mole of bioethanol after WGS reactor) included a solids circulation of 1000 kg/s and a fuel reactor temperature of 800 °C. To support a suitable fluid dynamic, the cross area was fixed at 0.05 m²/MW, which defined an inlet gas velocity of 5.6 m/s and supported the desired solids circulation rate. The fuel reactor was set at 13.6 m height to accommodate the size of four cyclones, and a pressure drop value of 24 kPa is proposed to facilitate a suitable dense bed height of 0.5 m.