(448c) Particle Properties in Techno-Economic Analysis of Chemical Looping Hydrogen Generation
AIChE Annual Meeting
Wednesday, November 13, 2019 - 8:42am to 9:03am
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.