(448c) Particle Properties in Techno-Economic Analysis of Chemical Looping Hydrogen Generation

Hydrogen (H₂) is considered as one of the most extensively used chemical intermediates in industry and a potentially attractive option for clean energy generation. However, CO₂ emissions from conventional H₂ production plants are significant, challenging the life cycle advantages of H₂ utilization. Thus, technologies are necessary to reduce or eliminate the carbon emissions associated with H₂ production while meeting the market demand in the present and future applications. Chemical looping hydrogen generation (CLHG) technology uses natural gas to generate H₂ with inherent CO₂ capture, which avoids contact between fuel and air (or oxygen) by utilizing a solid oxygen carrier to enable effective separation of O₂/N₂, CO₂ and H₂. CLHG can efficiently generate high purity H₂ with a high cold gas efficiency without the need for an amine-based CO₂ capture unit as required in conventional steam-methane reforming (SMR) or partial oxidation (POX) processes. In the CLHG process, iron-based metal oxide particles are circulated through a counter-current moving bed reducer reactor for full natural gas combustion to CO₂ and H₂O, a counter-current moving bed oxidizer reactor for reduction of steam by the reduced iron oxide to generate H₂, and a fluidized bed combustor reactor with riser for particle regeneration and transportation by air. After water removal, CO₂ can be separated from reducer flue gas and we can obtain high purity H₂ from oxidizer gas outlet. While particle is the key component of CLHG technology, this work focuses on the influence of particle properties, such as size, density, heat capacity, etc., on the overall CLHG process economics. Parametric studies of operating conditions were conducted to achieve auto-thermal operation of chemical looping reactor system and the pneumatic transportation of particles from combustor to reducer while varying particle properties. Specifically, this study developed the overall model of CLHG process with Aspen Plus simulation software. Several cases with representative particle properties and high process efficiency were configured. Energy and material balance information generated by the model was utilized to perform techno-economic analysis on the configured CLHG cases. The results indicate the requirement of particle properties to gain benefits of the CLHG system as compared to conventional H₂ generation process with CO₂ capture.