Efficient heat allocation in the two-step ethanol steam reforming and solid oxide fuel cell integrated process

To avoid a carbon formation in the ethanol steam reforming process from the polymerization of ethylene, a two-step reforming of ethanol via a dehydrogenation reaction and a steam reforming reaction for hydrogen production is proposed in this work. The study of using a CaO sorbent for CO2 capture to enhance the hydrogen production for solid oxide fuel cells is also carried out. Modeling of the two-step ethanol steam reforming and solid oxide fuel cell integrated process based on a thermodynamic approach is performed using a flowsheet simulator. The results show that the presence of CaO in the two-step ethanol steam reforming process has several advantages, such as having higher hydrogen yield, gaining additional heat, and providing a higher power output at a relative low reforming temperature. However, the exergy analysis indicates that this process has a higher total exergy destruction compared to the process without CaO because of the high amount of heat needed in the regenerator. Therefore, a heat allocation technique based on the first and second laws of thermodynamics is used to identify the optimal operating condition. The results show that when the reformer is operated at a temperature of 800 K and a steam-to-ethanol ratio of one, the minimum total exergy destruction to power ratio can be achieved and heat is also sufficient. (C) 2017 Elsevier Ltd. All rights reserved.