Chinyere Ezeobinwune

Modeling of Rotary Packed Beds for Reactive and Non-Reactive Systems

Rotary packed beds (RPBs) are used in a wide range of reactive and non-reactive applications. In this research, a 2-d, first-principles, dynamic model of a non-reactive RPB that is used for heat exchange between the outgoing flue gas from a power plant and the incoming air to the boiler/pulverizer of the power plant is developed. A 2-d, first-principles model of a reactive RPB is developed where a functionalized metal-organic framework (MOF) is used for CO2 capture. For the non-reactive system, a Ljungstrom-type air preheater (APH) is considered. Existing models for these rotating heat exchangers are typically 1-d. There are very few works in the existing literature where 2-d models are developed and validated with the experimental data. With this motivation, a 2- d dynamic model of an industrial-scale APH that considers variability of the transport variables in the axial and circumferential (i.e. direction of rotation) direction is developed and validated with the industrial data. Sensitivity studies to a number of key operating conditions such as the rotational speed and inlet flow rate and temperature of air/flue gas are performed. For the reactive system, a MOF-based RPB for CO2 capture is considered. In the capture section, CO2 from the flue gas reacts with the impregnated diamine while, CO2 is released by temperature swing in the regeneration section. As rapid rejection/addition of heat is required in the capture/desorption section to achieve large swing in the CO2-loading of the sorbent, an embedded static cooler is used in the capture section, while an embedded static heater is used in the desorption section where steam is considered as the heating utility. In the desorption section, steam is also directly injected for reducing the partial pressure of CO2. Mass and heat transfer models along with a model for the reaction kinetics are included. Finally, a techno-economic analysis is performed. Key operating variables such as the rotation speed of the bed and temperature of the bed are optimized for minimizing the equivalent annual operating cost of the reactive capture system.  

• Ezeobinwune C, Hughes R, Kotamreddy G, Bhattacharyya D, Siegelman R, Parker S, Didas S, Long J, Omell B, Matuszewski M, “Modeling and Techno-Economic Optimization of a Rotary Packed Bed for Post-Combustion CO2 Capture Using a Diamine-Appended Metal-Organic Framework”,  Virtual AIChE Annual Meeting, November 16-20, 2020