ABSTRACT
ABST R AC T In this paper we present a circulating uidized bed model for a continuous advanced oxidation process consisting of an adsorptive moving packed bed, a UV reactor, and a riser for hydraulic transport of photoactive particles. The model is employed as part of an optimization-based strategy to identify optimal equipment design parameters, exible operating conditions, and to aid in the selection of composite, photoactive particles with tailored system properties. The particles are to be circulated as a “working solid” for the decomposition of chemical contaminants in the presence of ultra-violet (UV) light in aqueous media. Based on our model, we formulate a nonlinear mathematical program with a minimum utility cost objective. Globally optimal solutions are obtained through direct search with interval
CONTENTS
Introduction ......................................................................................................... 318 System Modeling ................................................................................................. 319
Particle Construction ................................................................................. 319 Contaminant Adsorption .......................................................................... 319 Particle Transport ....................................................................................... 320 Photocatalytic Activity and Chemical Decomposition ......................... 321
Mathematical Formulation ................................................................................ 322 Results and Discussion ....................................................................................... 323
CFB Operation ............................................................................................ 323 Substrate Density and Photocatalyst Loading ....................................... 324
Conclusion ........................................................................................................... 325 Acknowledgments .............................................................................................. 325 References ............................................................................................................. 325
analysis; and these solutions can provide insight into optimal design and operation of the system. Our methodology is demonstrated for the design of a composite titanium-dioxide (photocatalytic)-activated carbon (adsorbent) material immobilized on numerous substrates. The particles are studied and evaluated based on their performance in the aforementioned system for the degradation of benzene in a contaminant stream. A sensitivity analysis is performed to identify qualitative trends implicit in the proposed mathematical model. Furthermore, we study the effects of small perturbations in the optimal particle design parameters on overall system design parameters, such as annular bed height.
