Computer-assisted tomography for liquid imaging in trickle flow columns

Publisher Summary This chapter describes gas-liquid flow imaging under trickle flow regime, which is one among the many hydrodynamic regimes, in which packed-beds may be operated. It occurs when the interactions between the co- or counter-current gas and liquid flows remain low. Simultaneous gas and liquid flows through unconsolidated beds of packing elements are encountered in a large variety of industrial processes. Roughly, these various applications may be divided in two categories. The first category groups processes aiming at bringing in contact gas and liquid reactants with a solid catalyst, in the pores of which the reaction(s) take(s) place. This field is covered by three phase (bio)reactor engineering. Typical examples are hydrodesulfurization in trickle bed reactors and biological treatment of waste water in trickling filters. The second category groups processes aiming at contacting a gas and a liquid to promote heat and/or mass transfer between these fluids. An inert solid packing is used to obtain a good distribution of the phases. Typical examples are gas-liquid absorption and distillation columns. The chapter discusses trickle bed reactors, trickling filters, absorption columns, liquid maldistribution, and tomographic techniques. It presents the results, which show that the high resolution, which can be obtained by computer assisted X-ray tomography allows the analysis of complex hydrodynamic phenomena occurring in different types of packed columns. The spatial distribution of the gas, liquid and solid phase saturations can be determined experimentally at a very small scale.