Date of Award
January 2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemical Engineering
First Advisor
Michael Mann
Abstract
Growth in global gross domestic product has historically been tied with high-carbon energy sources. Development of new low-carbon energy technologies is thus key to achieving a de-coupling of energy demand from economic growth. This dissertation evaluates the technical feasibility of a small-scale low-carbon solution referred to as Combined Hydrogen, Heat and Power (CH2P), a synthesis gas to hydrogen chemical looping process. The CH2P process is based on the steam-iron process and adopts multiple batch reactors to convert syngas in a two-step approach. First, the syngas is partially oxidized by reducing Magnetite (Fe3O4) to Wüstite (FeO) followed by complete oxidation in both a Syngas engine and Hematite bed (Fe2O3). The reduced FeO is then oxidized with steam to produce H2 and complete the first chemical loop. The hematite, reduced to Fe3O4 by the syngas, is also oxidized to Fe2O3 with air to complete the second loop. The partial oxidation of syngas with Magnetite is endothermic while the regeneration of the hematite is very exothermic and a key part of the CH2P development is the thermal integration of both steps. This dissertation focused on the performance of an engineered oxygen carrier containing over 70 wt.% Hematite, evaluated experimentally using a synthetic syngas composition. The rate parameters governing reduction of the engineered oxygen carrier were evaluated using a thermogravimetric analyzer and a packed bed reactor under different syngas compositions. The Weisz-Prater criterion and effectiveness factors for the process were determined, and optimal conversions proposed for the syngas composition tested. Next, an Aspen Plus model was developed for the process using the experimentally observed conversions. A detailed heat and mass balance was completed by varying the Syngas split between the Syngas engine and Fe2O3 reactor to achieve adiabatic operation of all reactor systems.
Recommended Citation
Nasah, Junior Neguieh Domkam, "Chemical Looping As An Enabling Technology For Low-Carbon Energy Production" (2025). Theses and Dissertations. 7530.
https://commons.und.edu/theses/7530