Portable nuclear magnetic resonance (NMR) spectroscopy and relaxometry are ideal technologies for providing process control in real factory environments. Real time process control improves the economics of chemical reactions in both batch and flow modes as product yields are increased. This work does not consider the less challenging method of factory analysis by introducing small flow rates (low Reynold’s number), slip streams or periodic mixture sampling followed by offline laboratory investigation. Rather, this work focuses on bringing the instrument to the factory to explore chemistry in native factory infrastructure, including high volume metal pipes with turbulent (Reynold’s number > 4000) flowing mixtures. NMR has already been used to study high viscosity industrial products undergoing laminar flow (Reynold’s number < 2000) e.g. toothpaste, detergent, tomato paste.[1,2] This work extends NMR to the study of turbulent mixed systems and both magnetic resonance imaging and immediate response, relaxometry based approaches to process monitoring will be presented. Results from the flow cavitation extraction of biomass serve as a benchmark example of this work as it was noticed that both the nuclear spin relaxation properties and sample viscosity of the biomass water mixture change during batch mode, ultrasound assisted extraction. A hydrodynamic, flow cavitation extractor based on industry standard designs was built and interfaced to a low magnetic field, permanent magnet based, NMR imaging system to determine at what flow rates conventional spin echoes and single point images fail. More importantly the extractor provides the landscape for developing new and resurrecting forgotten methods of NMR flow characterization that work in samples with Reynold’s numbers exceeding 4000. Finally, the details of an inexpensive, portable instrument which is suitable for this factory environment project will be provided.
References:
1. Kim, S; Garvey, C; Leary, T; McCarthy, M. Real Time Monitoring of Tomato Concentrate Processing Using RF Sensors. Advanced Nondestructive Evaluation II 2008.
2. McCarthy, M. J.; Bobroff, S. Nuclear Magnetic Resonance and Magnetic Resonance Imaging for Process Analysis. Encyclopedia of Analytical Chemistry 2006.