Session: 08-03: Solar Chemistry: Reforming, Base Chemical & Cement Production

Paper Number: 142264

142264 - Design and Thermal Testing of a Prototype Moving Packed Bed Catalytic Reactor 

Abstract: 

A high-temperature catalytic reaction can be used to convert propane into propylene, an important plastics precursor, through a dehydrogenation reaction. This reaction is highly endothermic, requiring high amounts of high temperature process heat. A reactor concept is being developed where this process heat is supplied by the solid catalyst particles heated with concentrated sunlight. Particles coated with catalyst can be heated in existing solar receiver, including falling particle and centrifugal particle receivers. The full system can also include thermal energy storgage. The particles act as both a catlayst carrier, with high surface area and small weight percent loading of active catalyst - in the case of propane dehydrogenation, a platinum-tin catalyst - as as a thermal energy carrier, providing the process heat to heat the reactant gas and drive the endothermic reaction. The reactor is a continuous counter-flow, moving packed-bed, non-isothermal reactor. Hot particles enter the top of the reactor and move downward slowly by gravity, with flow control at the bottom of the reactor limiting the mass flow rate. A flow of propane enters the bottom of the reactor and exists the top. Performance of this reactor relies on a careful coupling of thermal energy balance, chemical kinetics, and porous media gas flow. A laboratory-scale prototype reactor has been designed and constructed at the University of Maine. Particles are heated electrically and a displacement plate controls their flow rate. In this work, the design of the prototype reactor is described, and thermal test results are presented. The design calculations include a performance model to evaluate the temperature gradients along the bed and the chemical conversion. The chemical kinetic model has been validated against experimental results. 

The key design considerations are the balance between reactor dimensions, particle size, and pressure drop, even at small scale, and the heat flow rate matching between the solid and gas streams. Implications of these factors for scaled-up designs are discussed. 

Thermal testing performed has included operating the counterflow moving bed system with inert ceramic particles and a flow of air. At several inlet temperatures and mass flow rates of both the particles and gas, the heat exchange effectiveness is evaluated, and the temeprature profile along the bed length is measured at several points along the central axis of the moving bed. The measured temperatures and the heat exchanger effectiveness are compared with modeling results. This reactor will be tested chemically and a scaled-up system will be designed in future work.  

Presenting Author: Justin Lapp University of Maine

Presenting Author Biography: Justin Lapp is an assistant professor at the University of Maine in the Mechanical Engineering Department. He has over 12 years of experience with solar thermal and solar thermochemical technology. He earned his Ph.D. degree in 2013 from the University of Minnesota.

Authors:

Justin Lapp University of Maine
Thomas Schwartz University of Maine
Alireza Kianimoqadam University of Maine
Rollan Lemieux University of Maine
Temidayo Ogunjinmi University of Maine