(545a) Process Intensification Using Annular Centrifugal Extractor for Highly Exothermic Multiphase Di-Nitration Reaction

Here we present the application of Annular Centrifugal Extractor (ACE) as a process intensification tool (for reactive extraction) for the exothermic two-phase di-nitration reaction. ACE is a device which contains mixing zone (where both the fluid from the inlet gets mixed) and a separation zone (where fluid separation happens due to the density difference in the presence of strong centrifugal force imparted with the help of rotor). Several studies have been performed to predict the flow patterns inside the ACE. Various correlations have been developed to relate the effect of geometrical parameters on the hydrodynamic parameters[1, 2]. Though ACE has been widely used as the process intensification tool in area of polymers, pharmaceuticals and nuclear fuel as a separator, reports on their application as a reactor are very few[3, 4].

In the present work the ACE is being utilized as a reactor and an inline separator in a single device. Reaction is performed for different mole ratio (1:1 - 1:3.5 Reactant to nitric acid), phase ratio (10:90 - 90:10 nitric acid to reactant), rotation speeds and throughput (2 - 20 ml/min). The result obtained were compared with the reaction in tubular flow reactor as well as conventional batch reactor. Economic and safety implications were discussed for the scale up of the selected exothermic di-nitration reaction.

Initially, Hydrodynamics parameters (pressure drop, residence time distribution, heat transfer coefficient and mass transfer coefficient) of the ACE was determined for the different throughput and phase ratio by using model fluid Water and Ethylene dichloride (EDC). EDC is also used as solvent in the reaction. Extraction efficiency was measured for range of parameters selected above. Reaction was performed for the optimized parameter with high extraction efficiency at given throughput.

Due to high shear generated in the mixing zone and very good separation efficiency of ACE it can act as a very good reactor and separator. For the case of two-phase reactions where efficient mixing is required at particularly high throughput ACE can serve the purpose better. Highly exothermic multiphase di-nitration reaction chosen here require very good mixing to achieve good yields. The high separation efficiency of ACE can be utilised for the separation of two phases after reaction which can eliminate the use of different separator.

References

1. Kadam, B., et al.,chemical engineering research and design, 2008. 86(3): p. 233-244.
2. Vedantam, S. and J. Joshi,Chemical Engineering Research and Design, 2006. 84(7): p. 522-542.
3. Kraai, G.N., et al.,Angewandte Chemie International Edition, 2008. 47(21): p. 3905-3908.
4. Birdwell Jr, J.F., et al.,Separation science and technology, 2006. 41(10): p. 2205-2223.