SIMULATION AND PROCESS DESIGN FOR HYDROGEN PRODUCTION USING SORPTION-ENHANCED CHEMICAL LOOPING REFORMING OF METHANE

Abstract

This research focuses on the investigation and improvement of sorption enhanced chemical-looping reforming process for hydrogen production. Methane, CaO and NiO were employed as a raw material, CO2 adsorbent, and oxidizing agent, respectively. In this work, the effects of reforming temperature, steam flow rate, and solid circulation rate on the process performances of sorption enhanced chemical-looping reforming process were firstly studied. Subsequently, its process performances at the optimal condition were compared with those from other two hydrogen production processes i.e., steam reforming and sorption enhanced steam reforming processes. It was found that the sorption enhanced chemical-looping reforming process showed the best performance. In addition, the feasibility of adiabatic operation of reactors for sorption enhanced chemical-looping reforming process was considered. It was found that all reactors of this process could be adiabatically operated by adjusting some parameters such as steam feed temperature, air feed temperature, solid ratio from calcination reactor to air reactor, and solid ratio from air reactor to calcination reactor. Moreover, the influence of CO2 content in feed stream on an adiabatic operation of sorption enhanced chemical-looping reforming process was investigated. Higher in CO2 content in feed stream exhibited the negative effects on the SECLR process that was operated adiabatically such as less H2 productivity and H2 purity. For the reactors of sorption enhanced chemical-looping reforming process, their preliminary design was also taken into account. It could be reasonably indicated that the reactors of SECLR process would be 3-connected fluidized bed reactor which reforming and calcination reactors were carried out in bubbling regime while air reactor was operated in fast fluidization regime. The difference in diameter of each reactor depending on its operating regime was observed.