Modeling and Analysis of Sorption Enhanced Chemical Looping Biomass Gasification

Abstract

Steam biomass gasification has been considered the most favorable option for production of syngas. Nevertheless, the steam biomass gasification is inevitably problematic with undesirable CO₂ and tar formed during the process. Calcium oxide (CaO), when added to the gasification, could play the dual role of tar cracking catalyst and CO₂ sorbent, and thereby producing more hydrogen. The CO₂ capture process is the carbonation reaction of CO₂ and CaO to produce CaCO₃. In general, CaCO₃ can be regenerated at high temperatures and then reused within the cyclic process. Nonetheless, a major disadvantage of the steam biomass gasification with in situ CO₂ capture process is due to high external heat requirement in a regenerator. In this study, the sorption enhanced chemical looping biomass gasification, which is operated without heating and cooling system, for high-purity hydrogen production is investigated. Model of the gasification is developed using ASPEN Plus process simulator and used to analyze its energy efficiency performance. The results show that the maximum energy efficiency performance is 57.67% at the operating conditions of steam to carbon ratio = 2.6, temperature = 636 °C, CaO to carbon ratio = 1 and nickel oxide to carbon ratio = 1.06.